Ok, heres the things I'm having the most trouble with...........
1.Getting shields for quick settler production
More food = faster growth = more citizens to produce shields.
2.Building barracks and cultural improvements while making more than 1gpt
My first question would be: What victory condition do you want? I play a lot of Conquest & Domination, & I build very little culture. If I were playing for a culture win, obviously, I'd build more of the cultural improvements. My hunch is that your budget is getting eaten up by buildings that you don't need. Not every town needs a temple, library, barracks, cathedral and university.
3.EXPANDING(there are always other civs in the way on pangea, and not enough room on a standard sized continent)
Are you building lots of Wonders in the Ancient Age? Wonders are very powerful and lots of fun, but they're also expensive. When you've only got 5-6 cities, locking one of them into producing nothing but a Wonder is a big chunk of your empire. I'd suggest trying a game with no AA wonders. Build nothing but workers, settlers a few raxes and your military until you hit the middle ages. Why? Because if you're struggling with Warlord, then you are probably having trouble assessing when your empire can afford to build a wonder and when it can't. And I say that knowing that we were all new players once. In my first attempt at Warlord, I got caught in a wonder cascade and built one of the most expensive cathedrals ever. . . , while playing as the Mongols.
If you're not building many AA Wonders, then something else is holding up your expansion. Best to post a save if you can.
Also, on the issue of "there's not enough room," . . . My position is generally that there is enough room, but some tiles are just under "temporary management" by the AI.
should I go to war early to get cities and screw up friendships with other countries??
It depends. What's your chosen victory condition? What resources do you have, what do your neighbors have, and what do you need?