Well considering how far rendering can go I will say that YES some players can see your base. In fact because of a build height if there is one, most probably can. Underground is much better.
Don't quote me on this but I think that story blogs all need to be in one blog, even if they aren't I personally would find it more useful for organization.
It's not anything to do with the age, it's simply it can't handle minecraft super well. It runs normal frames for playing ability so I wouldn't worry about it unless you're trying to record or play other games.
Just go out and buy a prepaid visa or something of the sort. Does the same thing, and glitches probably won't happen on your end. Assuming you can buy a GameStop card I recommend only using the GameStop card for it's intended purpose on their website or in store credit.
With my experiences with 4k monitors I was able to get two, however personally on most games I don't see much of a difference. And they'll be cheaper in about a year when most games will be coming out in 4k anyway.
Just moved into a new house.
