[Beginner] Should I invest into facilities?

I would also bet on a scout looking for untrained only and that you can get for cheap. If one in 20 has reasonable potential and overtrains on your ground you're looking at a few millions per player.

Try to buy good value players with a couple of weeks before their birthday. That way, the following week or two their value will go up after the weekly update. Always aim to buy players between the ages of 22 and 25 to do this, preferably defenders or central midfielders. Never buy a player on the week of their birthday as their value will always drop the following week. Try to buy, as soon after the weekly update as you can, but never sell at this point. If you can, try to buy when VM has fewer users online and always set your auctions to end at around 7pm European time.

I decided to put some effort into my team and brought some old but good players and I look like i'm gonna be a top half team in division 4.

I was worried that I would have a hard time with older players but they can sell on really quickly which is good as I dont want to keep them too long with their age but it is slightly annoying having to replace them.

I have a game plan to get my facilities to the next tier of stadium and STF (grey) although getting to the facilities after that looks like something that wont be for a long long time.