I want to request a new game (and I found the link to do so) but I have a couple questions.

The game is actually a series, but I currently only have a run for one of them, should I request the whole series or just request it as a single game?

The request page seems to ask for an external link, the wikipedia link for the game only exists in japanese wikipedia, will this be fine or could I use the link for the publishers of the english version of the game?

The game is War of the Human Tanks

if you want to run the other games in the series, might as well just go with the series request so you don't have to go through the wait ever time. otherwise just request the single game.

yes, both the japanese wikipedia and the publisher's promo website are fine.