Yeah cables are going to have a ton of options. Don't sweat it tho, its pretty easy to sort out
Slimrun: *Edit, got it mixed up with flat cables. It's a thinner gauge wiring. Good for congested areas where standard thickness cables can start eating up room. It's almost half the diameter of a normal cable so it can be handy if you have a bunch of cables in a run.
Boots: This is in reference to the rubber that hangs over the plug retaining clip. Ideally it's there to keep the clip from snagging on stuff and breaking the clip. The flexboot is minimum protection but is more flexible so it makes it easier to press. Fullboot is a full cover but a bit more stiff to depress and Zeroboot is no cover. Personally I hate boots, some devices have a deep enough port that the boot gets in the way. It's personal preference tho, so go with what you like.
Crossover: Don't worry about it. Back in the bad old days of non auto sensing hardware, you needed a specific type of cable for direct connection between some devices (Computer to computer). Unless your hardware specifies a need for a crossover, it's not needed.
Plenum: This is cable rated to be used in air ducts and building conduits. If you're just running cable without the need for checking building codes, you don't need it. If you are routing through internal walls and the like, then check appropriate building codes for the type of cable you need to use.
If you're not doing anything that's going to require special cabling, then your basic Unshielded Twisted Pair (UTP) cabling is all your need. Look for something along the lines of 24AWG UTP Ethernet Network Patch Cable when you search. I'd recommend Cat6, but do at least Cat5e since I'm guessing your gear is all gigabit.