I agree with most of this. Clearly, House investigations need to begin in earnest on multiple fronts, in multiple committees, with Russia being the focus of only one or two of them. All of the other avenues toward eventual impeachment, such as emoluments or obstruction, can be handled separately from the House Russia investigation. The Dems need to start messaging that these other investigations are important in their own right and fight back against the media narrative that it's all Russia, Russia, Russia. This way, there is enough dirt on Trump to hurt him politically in case Mueller lets him off the hook re. collusion or other serious activities.
Where I differ is I would hold off on impeachment until one of two events occurs: 1) the Mueller report comes out and is reasonably serious or 2) further obstruction occurs by Trump or the GOP, such as by effectively torpedoing the Mueller investigation or through Trump pardoning someone from his inner circle. If the Mueller probe does not reveal Russia collusion but instead widespread corruption, this would qualify as impeachable.
Bottom line, the Dems need to keep their eye on the prize: an electoral blowout in 2020. I do not think impeachment proceedings are necessary between now and then for the Democratic base to remain fired up and to keep independents on their side of the fence. By resisting Trump legislatively, of course, as well as through multiple Congressional investigations, the Dems can keep the heat on and should be in good shape.
I'll go on to add, perhaps controversially, that I don't want Trump removed from office before the next election. I'll risk the small existential threat to democracy life as we know it to ensure that further damage is done to him and the GOP in the minds of as many American voters as possible. I'll happily let him keep fucking around for two years if it means total Democratic control of the executive and the legislature for 2021.