The question on whether or not Trump will be impeached has a simple answer - do the Dems take over the House in 2019 or not? Goopers will close ranks and go down with the ship because distancing yourself from your own President never works. If they hold the House, nothing will happen. FBI investigations go to DOJ for prosecution and they're not going to act on it.
Flip side is, if Dems do retake the House, the pressure to investigate Trump swiftly will be too great to overcome even to the most dithering of Dems (a good portion of them). While I think the natural inclination of mousy Dem officeholders would be to drag out investigations for two years until the Presidential election, they aren't going to get that chance if there's any whiff of wrongdoing. No, I don't expect the GOP to go along with this in the Senate, and barring electoral disaster they should still hold that chamber. Even if they don't there's not 2/3rd votes to convict EVEN IF Trump has been found to have personally colluded with Putin to influence election. It will however be hilarious to see pompous jacka sses like Hatch and McCain have to explain why they voted FOR a conviction over a bj, but voted AGAINST it over treason with our biggest foreign rival.