What do you mean by asking what we know about his agenda? We quite clearly know what it is based on his campaign...although it being an admittedly confusing and contradictory campaign.
And on the second bolded point, it's less about the normalisation of relationships and more about the fact that the US now has a literal fecking moron in charge who doesn't understand basic foreign policy or basic diplomacy. That should be worrying to Americans. Not just over Russia, but in dealing with savvy foreign powers in general. Putin is a shrewd, calculated operator who I'd imagine has little fondness for the US, and if he can see it destabilised under a Trump regime, or if he can see it pander towards him, then he'll jump at such opportunities irrespective of whether or not they benefit the US and the West. That should be worrying. The fact that Trump's likely Secretary of State has vested interests in oil in Russia should be a worry...because that's effectively someone who benefits more from a pro-Russian agenda than a pro-US one. Trump himself continues to demonstrate his lack of foreign policy knowledge by not bothering his arse to go to meetings...again, that's worrying, because he's potentially leaving it to his sidemen to deal with important info regarding Russia and other major countries.
And for the last part...I'm not going to argue that the US have used their force as a world power in a particularly negative and often outright evil and dictatorial manner as a sort of world policeman, but I'd ask you...would you rather live in a US-led world, or an authoritarian Russian-led one? Because for all the faults of the former, the latter, with its lack of tolerance towards democracy/any form of political dissenting, and by extension of that free speech and human rights, is a fairly scary thought. Again, some of what I've said applies to the US, but nowhere near to the same extent as Putin's Russia.