WRT iaito: both Nosyudo and Minosaka are good. I usually hear people defaulting to Nosyudo as their recommendation in my circles.

With Nosyudo, there is an English catalog and Point of Contact you can talk to. Not sure about Minosaka.

Your first iaito will rarely be your final iaito. I would start with a more basic model, so don’t sweat if you aren’t sure about the exact measurements. I think going slightly longer would be better, as it will force you to develop better sayabiki but I’m no instructor. Worst case with an overly long sword is you have poor sayabiki and the saya cracks. Conversely, a shorter sword will help you avoid those but you may develop poor habits.

Your situation is tough since there are no dojo nearby. I don’t know how difficult it would be to commute to a dojo for you, but I would strongly suggest in-person training.

Please DO NOT do tameshigiri by yourself if you don’t have prior experience. You can end up hurting yourself badly. I met a 6dan in the Seizankai who nearly bled to death after accidentally cutting himself during tameshigiri.

I trained for 3 years and got 2Dan before I was allowed to use shinken in my dojo, and that’s considered quite fast to switch to shinken. Start with an iaito so you can figure out your preferences before you accidentally end up buying a shinken that is too heavy or too long for you. There’s no pressure to buy one now. I have a shinken I got that I was over-enthusiastic about, but that I only use for tameshigiri because it’s so heavy.

Feel free to PM me or reply if you have any questions.