Don't worry, you can do it on Monday, no problem. Also you can do it online by yourself via the TM30 official webpage, but you'll need the landlord permit to do it online.
Yes, I updated by myself, just go to immigration. Also if you have a thai driving license you can use it in the hotels instead of passport and sometimes you don't need to file TM30 more times.
because I like many things about Thailand. I mean, moving non-stop from one country to another can be very annoying, and I like this country. Maybe others are better in term of taxation, but most of them are countries that I don't want to live for many reasons. You have also to enjoy your life and Thailand it's a wonderful place for it.
Everytime will be more difficult. Here in Thailand you xns optimize taxes a lot. If you don't remit a lot of money, you pay only a little. Or you can remit all the money one year that you won't stay for 180 days..