-Sealed bearings should be lubed with something like reelx or tsi 301? Just open it up, clean it, put a few drops in there and reseal?
-Open bearings packed with grease?
Sealed or open isn't an issue, it depends on whether it's a spool or side plate etc bearing and the type of fishing you're doing.
Which brings us to:
-Also noticed differentiating between spool and shaft bearing lubrication method. Regardless of sealed or open bearing types packed grease on any spool bearing will hinder freespool?
If you're looking for free-spool for casting, fly-lining livies etc, clean the spool bearings well and use a thin, high-quality lubricant like TSI301 or similar (ie ReelX etc).
Side plate bearings etc should be fully packed with a good-quality marine grease.
I'd generally fully grease all bearings on a trolling-specific reel...
-Are greases specifically marketed as drag grease necessary for greasing the drag washer or will any reel grease work? What makes drag grease different from a grease you would use for gears in a reel?
Yes. Drag grease is teflon-based. Any other grease will stick and undermine the quality of your drag.
There's a wealth of info on all these points in Alan's site - have a wander and you'll find plenty of illumination.
Hope that's of some assistance.
All the best, Justin