If democrats win the House in the 2026 midterms, what changes can be expected regarding Ukraine?

I ask as a foreigner.

And if democrats win both the House and the Senate? (I know, extremely unrealistic).

I know the House controls the budget, but for legislation to pass they need the Senate as well, then Trump has to agree to sign it.

A presidential veto can only be overridden if both Houses vote in favor of the proposed law by two thirds afaik. (are two thirds in the 100-member Senate 60 or 66 votes?)

BTW, is this a trusted, neutral source?

Are representatives and senators known for acting more freely from their party's president after losing a midterm if the president cannot run again?