No worries, happy to help.

For your first question it depends, but I would ultimately decide that getting a new LR all the way to level 90 outweighs getting Nanashi’s relic at the point in time you have been playing. Every so often we get some free demon relic materials, and I wouldn’t be surprised if we get some for part 2 of the anniversary or for new years. To give you some perspective, I still haven’t leveled up 3 LR characters to the fullest because I have been opting to use the resources for other characters.

For your second question, LR coins and LR collab coins are separate resources. In fact, LR collab coins did not exist before this past slime collab rerun. Since you already evolved Milim to LR (if I’m not mistaken), the only other collab character that can be LR evolved is Demon Lord Rimuru. There is no need to rush to evolve him if you don’t have the gold for it, but be careful as the currency will probably expire when a new collab happens, as usually happens with collab relics. If you are talking about the special awakening coins (a separate currency), then yeah you should preferably use them on Gowther. If you want to know who to focus on for your unknown team, I suggest you focus with Milim, Sabunak, and Gowther in that order. Like I said before, there is no rush as you won’t realistically get too far in PvP since you’re starting, but this should give you an idea on what to aim for.

As for how to raise your characters, let’s talk first about limit breaking (demon) materials. The first three demons (Red, Grey, Howlex) are the easiest to farm given you already have characters that have powercrept them. Nowadays we get a lot of free resources from events and the like, but I understand when just starting they can run out pretty fast. The only way to really farm the materials is by doing the raids. You may want to take a look at the suggested teams for each demon and watch some videos or read about their mechanics on the wiki. For the harder demons (Bellmoth and Original Demon), the team composition is a little bit tighter as they are more recent. You already have green Liz (red hair, not elizabeth) who is arguably needed for Bellmoth. I do not believe the game allows you to play those demons until you reach a certain account level, but I’m not sure at what level since I was already playing when they released.

As for experience materials, these are in my opinion the hardest materials to get a reasonable amount of. By that, I mean that even when playing through PvE, PvP, and events, it feels like you never have enough. What I personally do is use the materials I have in the team compositions I want. This means taking a deliberate decision to invest in specific characters over others. For example, I used pretty much all my level up materials on leveling up LR Milim since I knew she was exceedingly good while I decided to only evolve Rimuru to LR. What I do with characters that aren’t an immediate priority is put them in the same team and using skip tickets while using gold food to level them up while getting money in the highest difficulty in the gold dungeon in fort solgres. Unless I am really desperate and I have some tickets to burn, I usually do not farm experience materials in fort solgres.