How would I best go about clearcoating or clear anodizing a raw aluminum frame for a long lasting aesthetic silver finish?

Strip it with paint stripper and then scotchbrite, then just polish it with an aluminum polish.  No need to go further than that really.  I have 2 raw Kavenz frames and I maybe repolish them once a season.  

Removing the paint will be annoying and messy.  Wear PPE.  

Vapor blast or walnut blast. Sandblast is most likely too course.  Smooth out the finish with scotch Brit and wd40 if you want more of a brushed look.  Then find a paint shop to clear coat.

Probably doesn't matter either way, bearing seats should be unpainted.  I guess I'd leave them in if I was media blasting. 

I've heard media blasting can be too harsh on thin aluminum frames. I've had luck taking aluminum frames to get dipped at parts cleaners. Obviously you need to tell them it's an aluminum bike frame and not a cast iron engine block, because I think those require different chemicals and different tanks. My frame dip took a week from drop off to pickup and looked the bees knees.

i've stripped (and polished, if i'm ambitious) many an alu frame over the years. walnut blast works fine if you've got a local media blaster handy. otherwise lots of chemical stripper options out there if you want to DIY the thing. aircraft (aluminum friendly) stripper is quite effective, but noxious. there's a couple less toxic "green" options out there that do the job, but require a bit more elbow grease (multiple applications, etc). mothers mag / aluminum polish is the shit if you want to make things shiny afterwards.   

What kind of frame is it? Maybe find out who you plan to use first and ask them as they may have some specific guidance about how to prepare it best

some more tips here - https://anodizing.co.nz/questions-anodiser-anodising

Nope. That's one of the nice things about dipping, you don't have to cover or prep anything. You just have to pull parts off, which you'd have to do for painting anyway.

Commencal used to clearcoat their frames with lacquer and that basically fell off if you looked at it funny. Bird did the old AM9 raw as welded and it gains a nice layer of patina (polished where you load it with your knee, tarnished elsewhere for example). The newer Aeris 9 is coated and they were talking about a clear coat powder coat at some point. It's holding up to the abuse well for what it's worth. 

Strip with paint stripper like others have said, polish with various grit scotch brite pads, and clear coat with KBS diamond clear coat. It’s $30 a can and is a great durable product. I coated my raw steel Druid frame with it and so far not a single scratch or chip, even after park season.

Absolutely not, if we're talking about a full suspension frame. You will need to completely disassemble the front and rear triangles, remove bolts and linkages, etc. I don't think the parts cleaner with the dip tank wants your old bearings, grease, and loctite from your frame bleeding into their tank, and they're not going to be able to do the final spray down and cleaning on the front and rear triangle with your linkage in the way.

A local powder coated has stripped a few frames for me, it's run me around $40, and then I'll clean it up with purple scotch brite pads. If you want to take it a step further, Mother's car polish makes it almost annoyingly bright and reflective.