A few pointers
If you are framing 12x16 in 12x16 frames look at the glass. Is the glass plain or non-reflective (NR). If it is plain do not use gloss paper (or fuji pearl or kodak metallic) as the gloss surface will, in time stick to the glass, or at least get strange marks...
If you get your prints mounted onto card or foamex they will stay flat - unmounted prints will sometimes ripple. You can also get mounted onto aluminium - dibond is the usual material - which is 3mm thick - a sandwich of old car tyre rubber with a skin of aluminium on both sides.... very light, very rigid. If you have the print laminated as well you could frame without using glass or back....
If your screen has been calibrated, you can use labs that don't colour and density correct - if you are unsure of your screen a good pro lab will be a better choice.
There are a number of printers that write onto photo paper - Fuji frontiers which can write onto paper 12" wide - Noritsu which will normally work up to 12" (though they also do a very rare 24" x 36" machine. The Lightjet come sin a number of sizes - but often up to 54"x96" - Lambda write as the paper transports so can print on 30" or 52" to any length (limited by the rolls of paper). There are also zbe which work on the same principle. There are couple of others too.
Now the printer used is not that important - it's the skill of the people who work them - much like a camera - owning a Nikon D4 won't make you a better photographer! However, labs that own Lambda printers (which cost £24,000 a year just for the maintenance contract) tend to have very skilled staff for obvious reasons!
Virtually every labs are looking for jpeg files (TIF are accepted at some, but there is NO quality advantage unless you have text and graphics). sRGB is the ideal colourspace for most - as it's the closest to the colourspace of the printer. Some may work from RAW - but that would require a proof to check they've done it to your taste and would cost!
As for surfaces you get lustre (which has a texture and sheen), gloss, mat (no real texture and no real shine). Them you get metallic (kodak) and pearl (fuji) which have a gloss surface but the paper has non-white base.
On inkjet there are loads of surfaces - you can print of paper of different types from wallpaper material through to almost card - metal foil - and some inkjet printers will work on solid materials - I saw one once printing onto 18mm MDF!
