Your wife is right - You will certainly find a hotel, but I would not wait until September to find it. Inventory may be released later this year - perhaps six months and three months in advance. That said, it's a popular time to visit Kyoto, so it's a good thing to secure a reservation in advance.

Currently, on hotels.com, I see availability at the Hyatt Regency, Okura, and Granvia. I don't know if these are the major hotels you're looking for, but they're good. They all have concierges who can help with restaurant reservations. I believe Citadines also offers concierge services.

Normally, I find myself urging people to avoid unnecessary hotel changes ... It's a hassle to be constantly packing and unpacking. But with such a long stay in Kyoto, you might consider spending a night or two at a more uniquely local accommodation. If you're a high roller, you could try a famous ryokan. If you're a more budget conscious traveler, you could try a machiya (traditional house). You could also stay at a temple, if that appeals.

As for your search for an interpreter for 30 minutes work per day - You could try contacting one of the professional guide companies on the JNTO site:
http://www.jnto.go.jp/eng/arrange/tr...deservice.html

However, I really don't think you'll need this.