The LPK is probably the most work to install. Everything else you listed can probably be installed without tools (pulling the pins should be all) with the exception of the flatline barrel, you may need to loosen the front screws 1/4 of a turn to free up the stock barrel and make it easier to install the flatline, then re-tighten the screws when the flatline is in.
The nice thing about the A-5 barrels are that they are 1/4 turn removal barrels - not threaded. I leave the front screws a little loose (say 1/8 turn) so that I can quickly and easily pull the barrel under fire and clean it, then slap it back in before anyone can see that I pulled it.
Keep in mind that if you go with a conventional barrel the effective length of the barrel ends when the ports begin (the little holes along the barrel); with this in mind you can see that the stock barrel is only around 4" long - I don't know why tippmann does this, its useless. Well who are we kidding - the reason for this is to make you buy an after market upgrade and spend more money on them. Don't kid yourself by thinking that they don't know what they are doing, its a way to squeese us for a fiew more dollars.
You should shop around for the best price - this site is not the cheapest - you can get the same kits on other sites for less.