He's saying it's better to spend on other items that give power before increase battle armor rank 7+ since the spending required to level the battle armor costs a lot more if you were level something else. For example: I know this is random number and might be wrong but let's say it requires 10k coupons to level rank 7 to rank 8, that 10k could be used else where and might give you more power if you were to increase the battle armor rank.

Currently in China, they have the shops combined into a new type of shop that has power items and yes you c*e the coins to buy them. To earn these coins, you just have to do all of the dailies.

Like I said in my second point, there will be an update to the shop and you will be able to buy advance threads. If you want more information, search in youtube and use terms like naruto online china (Memo has a video on the shop update) to find videos of this.

Apparently around last year, they had updates that helped f2ps (this shop update i was referring, the scroll system, and having the time-limited recruitment (use stamina to get keys) for to piece ninjas like angel konan, edo hiruzen, shisui and that event showed up every two weeks) Then sometime during the summer, they focused more p2w so they focused on spending events and stop having the time-limited event show up as frequent so you can't expect good things to happen all the time.

If you are worried that Oasis won't add the shop or the scroll, they can't do that since it's a feature (so far they haven't missed anything as of yet, rather they are delaying the release) to the game rather than an update to an existent feature. Limiting how much frags and increasing the price per frag might likely happen when we get the shop.