Or can I just buy the unshielded cat6 RJ45 connectors?
Motorola 2210-2 DSL modem -> Cat5e -> US Robotics Smart Gigabit Switch 8 port ->
garage (separate building from living quarters)
Cat6 shielded outdoor runs here ->
Asus GX-D1051R1 5 port power-saving Gigabit Switch -> devices with Cat5e.
The problem was the Cat5e previously used got water in it, since it was not outdoor rated I assume (cracks from Sunlight formed somewhere me thinks).
Also, is it okay to put one more switch inside to shorten the run? I just read for the first time that this can actually degrade the signal. I was thinking of adding some more juice to it with a switch but this may not be correct.
Also, if I need to use couplers with this stuff later (inside) will I need shielded Cat6 couplers?
The cat5e in the network is all unshielded indoor rated patch as far as I can remember/tell.
Although a lot of outdoor cable is shielded it is not a requirement. The shielding is used to protect against induced electrical interference which is actually more likely to happen indoors when you run the cable near other things...like high frequency power transformers.. that may cause signals to be injected into the cable.
Mostly outdoor cable prevents against damage from the sun and the soil Since the inner conductors are also coated in plastic water generally does not cause large issues until the plastic is degraded by something else. It depends on the cost of labor to replace the cable. It may be more cost effective to just use indoor cable and plan to replace it every few years.
It will make no difference either way if you put in extra switches. They do delay the signal some tiny fraction of a 1ms but you would have a hard time detecting it. You will likely get no difference in distance there really is no power being send over the wires the devices are detecting a difference in the voltage.