Reddit mentions of SHIMANO Altus SL-M310 Gear Lever Right Black 2014 Right Gear Lever

While some shifters are better than others, at this price point, they all will be about the same. If you want thumb shifters, that is a perfectly valid choice. There are also some trigger shifters out there, as well as grip shifters if you wanted to keep that style. As long as the shifter is shimano compatible, and 7 speed, it will work with your current freewheel and derailleur.

>As for what you described with the current drivetrain, what i think I'm seeing you suggest is 'clip the front derailleur off/remove it, leave the current crankset on with the chain at the middle gear since even though not optimal it current funds can be better spent elsewhere.' Am I reading that right?

No. The bottom bracket axle length will determine how close to or far from the frame the chankset is. This article on Chainline may be of some help.

What I was suggesting is that you can still change the crankset, and leave the derailleur in place as a chain guide (tighten the limit screws to ensure that the derailleur is centered over the chainring). They make purpose built chain guides, but the derailleur is already there and will work, so free chain guide.

As far as the rear derailleur, you have a claw mount derailleur, so for anything "better" than what you have, you will need an adapter. As far as upgrading the derailleur, I would personally go for something along the lines of the Altus M2000 or Acera M3000. Note that these are "9 speed" derailleurs, but the cable pull is the same as 5-8 and the shifter dictates the "speeds" shifted, so they will drop right in.

Pedals, Rockbros are the current king of the inexpensive. They come in a few colours, so you can match that to your taste.

Weeding the bad out is sometimes as easy as reading reviews, yes. However, look beyond the amazon for reviews. I generally prefer a video review, so I frequent YouTube for them, but google/duckduckgo can usually find a few forum posts as well that will answer questions.
It is also sometimes as easy as knowing a trusted name, and using their part over a shady one. Shimano and Sram parts are usually trusted and reliable on the drivetrain. Rockshox, Fox, and Manitou are good for shocks and forks, but Suntour is also sometimes good. There are more brands that are great, but on the low end price point, just play it by ear.