5*, lvl and manual sp input are working fine with GG. To avoid error 3001, you either need to have xposed with rootcloak installed (I haven't really been successful on that end so I'm just looking into alternatives to avoid safetynet) or to work fast enough to avoid detection (meaning, you edit one thing at a time, directly synching after you did something. Personally I've been doing it like this for weeks and GG has been doing well for me so far).
1: No. Shards and Crystals are currently server side and as a result of that cannot be modded for now.
2: I have yet to see someone add unlimited SP, I just do it manually. To do so, I first find the heart value with 100/101 or 228/229 (237/229 should work too). Once I've done that I go to the address and select the two adresses above the heart value. Of the two adresses you've selected, you pick the upper one (the one furthest from the heart value) and you change the value as DWORD to get the SP you want (I recommend you do 900 to 999 max). After that you edit the other address as DWORD to 0. If you've done everything correctly, the addresses should show the value you've chosen (for example 900) and 0. Now all you need to do is learn a skill or equip/unequip a weapon or skill (I recommend you deselect and then select your unit so that the right amount of SP gets shown if you're going to learn it a skill). If you're not taking too long you can teach a unit like Lyn, that needs a lot of SP, all skills and even give some SP afterwards in case you want to inherit stuff.
3: What do you mean by hero movies if I may ask?
4: People are still in the middle of finding the way they can change the predetermined values. I suggest you wait a bit until there's a surefire method. You can also just join people who are working on it to speed up the process if you're willing to.
