If your server is still brand new, and you already have jonin minato, 4* gaara and iruka, I dont think that you have to worry about anything, it will work out with/without bond skill. Just get your six path on arena and start earning frags from there.

Kakashi Kid you will get when the server merges (about 2-3 months from Server start) . He is good enough especially for new server - even without his bond mystery.

At the start of a server, when no one really has much else he's obviously going to perform really well, he's not the best choice but it's not a terrible choice to pick him up as it also allows you to work towards getting the items required for you to bond mystery him now as your server will eventually merge, I believe all newly created servers are merged within the first few months.

I personally think he's a toaster of a ninja without his bond mystery xD

Instead of Iruka I would use Shikaku. You get amazing chase synergy with minato. 40 chakra + immobile. which will help to fire off minato+ gaara in round 2.

The problem about Shikaku is, in order to get him I'd have to use A LOT of moon scrolls to get Choza Akimichi first. And I'm using my moon scrolls to get cave keys, saving 1050 of them for the eventual rebate (I'm hoping it comes, and I have enough by then).

So, for now, doesn't seem like Shikaku is a possibility... Having 30 seal scrolls in hand, I could try pulling them on seal treasure to see if I get kurenai and maybe Obito [Shonen] as a bônus, but that doesn't seem really worthy as I can just end up getting Zabuza, 20 Guy Frags and Karin or whatever.

Thing is, I'm Fire Main right now (lv 53), and I'd use Jonin Minato with Gaara and Shikamaru [Chunnin] or Hinata until lv 60, when I'd turn to Wind Main and use him with Gaara and Iruka. Is it worth spending all my 5k coupons to get him right now? Or should I just go for the speed of light clothing and save my coupons?

We don't know if he'll remain this cheap & that'll be effecting this answer- my immediate answer considering your circuumstances, yes I'd get him, purely because he will eventually evolve into something amazing that you can make use of, sure you wont be able to use him effectively right now- but lets be honest, there's not much you can uuse effectively right now so it's a mute point in all honesty.
There's also no ninja you cann use that would beat him anyway, so it's a case of do YOU like him? If so, pick him up, it's not a purchase you will regret as he'll only get stronger with time.

There's nothing you can grab that will be better than him for this cost.
That's not to say if you saved, you wouldn't be able to pick up something better in the future- but that's the choice you make, Shisui would in my opinion be the better choice for you right now in my opinion- but he'd be triple the cost.

Thank you a lot! That's an amazing answer and really helped me. I'll be getting the minato now, and then I'm saving coupons until I can get 5k Madara. So I guess in 2 months or such I'll be able to get both 5k Madara and Minato's bond mystery after the merge. That should put me in a good position for a good time.

I just had to check, yeah true. I didn't even know you had to get Choza first. Wow he was super easy and cheap to get before this.

Depends on you if you wanna spend the seals or not. I never advise someone what to do with their seals. You can buy Obito from the blackmarket, you should have him before the merge.

Good to hear, that's what I'm working toward as well