Who can help me understand a little about SEO?

Question

URL Handling

1 - Canonical where to do if 2 domains? .by, .ru?
2 - If I decided to change the semantic core, all links contain the word "beautiful-TV", and then I suddenly realized that I need the word "long-TV" - correctly do 301? or 410 and recreate pages? or how is it generally smart, so as not to lose weight and "pump" pages?
3 - Broken 404 links of the old site (we changed the engine) do you need to do 301 in a smart way or just delete it if the name of the article changes or the article is simply deleted?
4 - And if the TV is in two categories, what should the breadcrumbs look like?
5 - If we have a new request in the semantic core, then for each request we need to write an article, a publication, and preferably PR in groups? As I think, for every request to do this - my roof is leaving

Answer 1

1) if the content is the same, on ru, otherwise you will be very popular, but in Belarus
2) with the same text, only the URL will change? 301, but the idea is bad, in general, the keys in the URL - xs already affect what for 5-10 years (well, except for the snippet) 3) if the link began to lead to 404, delete it, change the content on the
link is undesirable
list, but in general, usually one crumbs go by manufacturers, here they are more important, because there are many TV carriers, and a specific specific manufacturer is unique
5) well, if there is no content, how will the page match the query? in groups - xs, like it works, well, if it works - do it

Answer 2

1) that's right, we want the site to be in both Russia and Belarus. and there and there in the top on our request. is it possible?
2) that's right - I have a link krasivi-televizor at my article, and I suddenly realized that I need to move on the "long TV". And write new articles vlomy. I understand this - is it better to write new articles than to change urls?
3) I did not find "delete from the index" at all in Yandex, although it is written everywhere that just wait - it will be deleted by itself. I still have a section on the site that hasn’t been in Yandex for a year now. and at the same time, every second person says that a lot of 404s is very bad. And the whole old site was now littered with 404s, thanks to Google I deleted them all, but in Yandex they didn’t go anywhere, and there are 6000 pages marked 404, fucking Joomla.
4) ahh exactly, super thought. you mark in all categories, and the one that is alphabetically earlier is the one you show. super!
5) well, I was more interested in the question - how do you start moving forward on some request? start with an article? or stomp to do an interview? and post this article in all contacts? or buy links? or look for friends with whom to do joint promotion through articles, referring to each other? Where to begin?