If you're active enough, you should be able to farm 100 medium refines for every 4 weeks (typically the refine rebate shows every 4 weeks or so) so rebates isn't a p2p event if you are willing to stockpile items. Also, you may need to switch mains since lightning is terrible with minato in comparison to the other mains. Make sure you stockpile potions when you need to farm awaken materials, esecpially during 2x during the weekends. There are a couple of guides out there for what you should be doing as a beginner.

Worry about increasing your power while getting ninjas via treasures. Ninjas like the barrier ninjas (mei, onoki, darui, kazekage, or danzo) in kage treasure, the 7 swordmens via gnw treasure, han in jinchuriki treasure and roshi treasure are ninjas that everyone should at least have from one of these treasures. You'll eventually come to a point where you need to save for event ninjas but there would be for a while.

Lucky dice and missions are great events to buy power items and you get free items while spending. They should be back two weeks from now.

Don't try to get 4th raikage at the moment. It takes about 800-1200 just to get a 50% chance to get him. Sage natuto isn't as useful in comparison to before because of the ninjas from the treasures I mentioned. You need to figure out what ninjas work esecially since you level too fast to level 80+ where thats you usually start to experience harder matches becasue you'll face players who know what they are doing.

Since you have hokage minato, figure out which ninjas would work with him and from those two extra ninjas, which main would work.

Yeah he's far behind in order to be competitive. I have a bunch of players like him in my server. If he isn't attached with his server, he could switch to a new server but he should at least know what he should be doing so it doesn't lead him into the same situation as he is dealing with.

Yeah definitely below 50k for sure, not even 45k, here are some of the players on my server who don't understand the game, therefore not level freezing. Even if they were to use their coupons on power as a f2p, they would not have enough to increase drastically since they leveled too fast to allow themselves and won't be able stockpile coupons and power items.