Upgrades and Customizing - First purchases!

Ok, it's been almost 2 years since I last played but a bunch of us (all in mid 30s) were chatting it up and realized we've all been wanting to play but just couldn't find people in our circles with the same interests. Anyways, long story short, the one guy with 10 acres of wooded land is going to host and 10-15 of us (all newbs or old intermediate players) are going to crash there a few times a year for a fun game. We're looking at milsim as our goal (we'r all nerds so we wouldn't have it any other way) and I'm just wondering about my basic setup. In the past I've always rented but this guy's place is out in the boonies so better to own. Again, we're just a bunch of friends looking for a good time, not looking for anything overly competitive or tournament bound.

On that note I picked up a used x7 phenom (stock) off the classifieds and am wondering what to get next. What do you guys think:

I always recommend that players use/test their marker stock before spending any money on upgrades so they don't end up buying stuff that eventually gets taken off of the marker and stuck in a drawer somewhere.

- Scope/flashlight/laser/dot: having limited functionality I don't plan on getting any of this stuff until we commit to hardcore milsim or I want to do some fun modding.

Scopes are essentially useless for aiming because of the arcing trajectory that paintballs take enroute to the target.

They can be useful for spotting however if the terrain allows.

Flashlights can be useful for clearing buildings or night play

The beam can be noted by opponents from much farther away than it can illuminate opponents.

Lasers are pretty much useless outside in daylight but can be fun inside or during lower light conditions.

Remember the laser can give your position away.
Be aware they aren't allowed at many commercial fields because of the danger of eye damage from shining them in someones face.

If by dot sight you mean one of the various types of red dot sights opinions differ.

I consider them useful for making sure one's first shot is on target during ambushes, others see know purpose for them at all and prefer to just open fire and aim by watching where the balls go.

- Co2 vsHPA: Although I'd like to go HPA I think we're all going to go CO2 and just get some big tanks to share from. Because there is no refill site within hours and we're out playing in the boonies then I figured this was best.

CO2 is probably your best choice based upon the description of where you will be playing.

In warmer weather it gives you more shots from a comparatively sized tank than compressed air will.
However, CO2 is temperature sensitive and is not the best choice if you are considering winter play.

I wouldn't recommend it for anything much below 55*; but I'm not a fan of cold weather games either.

If you do go with CO2, you will need several additional items:

The equipment required to fill smaller tanks from the big tank.
A small scale for weighing the smaller tanks before and during filling to avoid overfilling.
A larger scale to weigh the big tank so you will know how much is left in it.

It is also important to know what you're doing when filling the smaller tanks as improper filling can have potentially disastrous results.
What I would actually recommend is that each player purchase at least two 20 ounce tanks and make sure both are full before each outing.

This should be more than sufficient for a day of play.
Or, if 20 ounce tanks are too heavy/throw off the weight of the marker, then multiple tanks of smaller sizes could be used.

I don't recommend using anything smaller than a 12 ounce tank because the smaller tanks are more prone to overheating and blowing burst disks on hot days.
With this in mind, always store the spare tanks someplace out of direct sunlight/cool while at the field.

I used to keep mine in a cooler in the shade.

It's also a good idea to have spare burst disks and spare tank o-rings handy.

Actually, out in the boonies, everyone should have a tool kit with spare parts, oil, rags, water for cleaning up masks and gear, etc.

- Remote line: I saw this as a worthwhile upgrade asap as our sessions will be long and possibly even last multiple days. Figured dumping the weight of the tank off the gun would definitely be worth while. I saw this simple package and was wondering if it's decent quality, the price seems better than buying it all individually:

http://www.badlandspaintball.com/4-plus-1-paintball-harness-with-deluxe-remote-20oz-tank.html

I won't recommend specific equipment brands but I will note two things:

A remote line can act as an expansion chamber for CO2 which increases efficiency and helps prevent the velocity fluctuations inherent to CO2 use.
Having a slide check on a remote to turn off the air supply at the marker end of the air line is very handy.

- Mask: I'll visit a local place and find one I like, don't want to buy this used.

Never buy a used mask.
The mask is the most important piece of equipment one can purchase; this isn't the place to try to save money.

There is a thread specific to masks in the New Players section and it is a very useful read.

- Performance upgrades: From what I've been reading the x7 phenom (electro) seems to be good enough as stock for a newb like me. I wasn't really planning on changing anything until I've had some time to use it. Anyone have an opinion otherwise?

Again, I recommend that everyone play with their marker stock before adding upgrades.
Also, if you are getting the electro, then the R/T is out of the question.

- Other: The only other stuff I was thinking of was a strap for the gun

A sling is very useful when running remote because, since the marker is attached to you by the remote line, you can't put it down easily. The sling allows you to free your hands for something else if necessary.

Any other input from the more experienced guys?

There is also a very handy article in New Players about paintball in general that I recommend reading.
You all should have at least two chronographs available every time you play.