Welcome, and congrats Cloakndagger! I may have seen you yesterday at Blade West!

1) We have several sheath makers here on the forum so you can probably get the most expert opinion from them.

Cordura/nylon is the least expensive and can be found with pouches for storage on the sheath. Usually they have a plastic liner that allows them to fit many different blade types. I prefer to store my knives in at least a cordura sheath versus the card board sheath that the Busse knives typically come with. With a good size choice, retention can be good. They work fine but are not as light nor form fitting as a good Kydex sheath.

Kydex is the all weather miracle. Easiest to clean and maintain IMO. The Tek-lok gives a variety of mounting positions. Kydex is my all weather "go to" choice. Kydex can scratch the blade coating/satin finish however.

I love leather sheaths. I prefer leather sheaths for their beauty, individuality, and comfort. A nice leather sheath just feels great, a lot more comfortable for me than Kydex because the leather gives as you move. You can get leather wet occasionally and it's no big deal. If you're going to be out in wet weather a lot I would consider Kydex. I know Troy (360 Joules), the guy you bought your Ratmandu from, prefers Kydex for the Pac NW weather.

2. There was a big thread on this recently. Sorry but I can't remember the keyword to find it. I have a bunch of pocketknives that I carry in a random rotation, everything from an old Benchmade miniAFCK, to a Camillus Heat, to a Benchmade Osborne 940, to a new Benchmade miniSkirmish.

Again, welcome to the Yard!!