It's a Ruger you're probably looking at a vary reliable gun. From what I've seen its much slimmer and lighter then the P series. I'm a fan of the crossbreed holsters but there are many different makers that will work very well. I don't know for sure but I haven't heard anything about being picky with ammo. Congrats on a good gun!
I have an SR9 and have found the Fobus paddle holster to be very comfortable. They may not list one as availabel for the SR9 but the HK-1 fits perfectly. I have found the gun to be reliable and shot mostly Winchester FMJ ammo with it.
I've had one for a couple of months. Be aware that you "could" have
chambering issues the first couple of hundred rounds because the gun is really tight from the factory.
Having said that, it's a beautiful, functional, and accurate pistol which is a joy to shoot. I've not had one problem with mine.
Mine was really dirty from the factory so you may want to clean it up before you take it out.
There are alot of good types of ammo out there, your best bet is to go to the range and try some. See what you like best and what your new toy likes best. Speer Hollow points are what I use in mine or federal Hydroshocks