- Yes, objects in thingiverse usually doesn't include their size and this can require extra effort to obtain.
- There are several options to scale objects to fit your printer. You can often do that in the slicer or using a separate program like meshmixer.
- The bed size is not the only (or maybe even primary) limitation you will need to consider when printing an object. You also need to think of your max height, nozzle size and for your choice of material your will need to consider things like you max extruder and bed temperatures (or even have a heated bed), nozzle type, etc.
- You should be able to print just about anything on thingiverse; but, the limitations of your printer will affect HOW you will have to print it and whether you will be happy with the final product.
I have heard of plenty of people the have smaller printers and it was the right place for them to start. Having a smaller printer that performs well for you will be a much better experience than a larger printer that performs poorly.
Whether the Monoprice Mini 3D v2 printer is the best printer is something only you can decide. Read and watch the reviews, they can be a great source of "perspective". I know we all have limited budgets and there are certainly way more things you can print with a printer than you can without one.