A Linn like you're considering is one of the best values on today's current used market. Others might include Sota Sapphire, and Well Tempered Classic.
If you plan to stick with the K9 cartridge, then nearly any phono stage will work, because it is a normal MM cartridge. Of course, better phono stages will make the sound better, because they will do a better job of getting the information into the preamp. There are many on the market, and there is a lot of info on this subject in the archives.
While wall mounting is needed for some individual situations, the original Sound Organisation TT stand was designed for the Linn LP12, and provides the lightweight, rigid stand that the Linn prefers. I'd recommend seeking one of these TT stands out, but if you have to, you can use a wall mount. I think the stand will sound better.
If you plan to stick with the K9 cartridge, then nearly any phono stage will work, because it is a normal MM cartridge. Of course, better phono stages will make the sound better, because they will do a better job of getting the information into the preamp. There are many on the market, and there is a lot of info on this subject in the archives.
While wall mounting is needed for some individual situations, the original Sound Organisation TT stand was designed for the Linn LP12, and provides the lightweight, rigid stand that the Linn prefers. I'd recommend seeking one of these TT stands out, but if you have to, you can use a wall mount. I think the stand will sound better.