Questions – Should “How is Your Weekend Looking” or “How Does Your Weekend Look Like” be Used?

"Who was with you?" and "Who were you with" are equally grammatical and natural, and carry only a very slight difference in meaning.

"Who was you with" is ungrammatical for most English speakers (since it corresponds to "You was with X").

The claim "prepositions in questions usually come at the end" is wrong without some further specification. If the preposition logically precedes the question word (who, which, what etc) then in colloquial English it usually goes to the end: that is, most people would say "Who did you go with?" rather than "With whom did you go". But this does not apply when the preposition goes with a noun phrase that is not the question term ("with you").

Answering this question, and this one, it did occur to me that there is a gap in English id you want to express a particular occasion when something happened in the form of a question. However, in real life, you would be able to work around it based on what you already knew.

For your Ukraine question, I would say:

How many times have you been in Ukraine? [If this is their 5th trip, they will answer with '5'.]

If you want to deal with events which happened on an unspecified occasion during one of the trips, things get a bit trickier. But actually, your 'hilarious' suggestion is perfectly good. It sounds a bit formal, but grammatically it is fine. Here are some alternatives.

On which occasion was it that it rained every day?

Which time did it rain the most?

Which visit was the rainiest?