if its not too much trouble, do you have general advice that would be helpful for someone just starting the game? Feeling sort of overwhelmed with all the systems and stuff being thrown at me
First thing's first, the game is pretty grindy. This is ameliorated somewhat by the fact that later enemies are pretty solid EXP bags and a variety of ways to mass-murder enemies on the cheap. In the beginning, though, the best way to safely level up is to do a bunch of math and have your MC creampie girls, then run around and fight in the Meadow (starting area you can find in the northernmost Guild portal). Abuse the fact that you can completely heal your health and mana by resting in the Merchant girl's tent; a little ways north, there's a small fort that has its own bed and savepoint. The monsters inside are pretty easy to beat, and there's only like 3 that you need to defeat before yo can claim the area as yours.
It's rough at first since it forces you to hit the ground running with basically no starting point and no guide whatsoever, but there's no need to familiarize yourself with the abundance of blacksmithing materials or level resetting or any of that until you've got a bit more experience under your belt. Side note--I recommend only having sex in your ranch or your home bed, since doing it there for whatever reason allows you to keep all your skills even when you go back to level 1 (as opposed to forgetting everything when you have sex anywhere else).
Misc note, some of the equips mention "Only can be equipped by G1" or "G2 cant equip this."
Refers to Grade. Basically the ranks of your monsters, e.g how advanced of a species they are. You can check this by going to your Ranch and interacting with the warp station, then select Party Formation. It'll appear at the bottom of their info blurb.
Also is there a way to switch Makina's party screen portrait to the default one instead of the sex slave one? I noticed she now has a skill called "Display a Standing Picture" but it doesnt seem to do anything
Press Q to access Quick Settings. At the bottom is an option called Character Avatar Setting. From there you can choose whether to show the pregnant sex slave or regular displays.