I guess both can be answered using my old PB, chainsaw strats on lance are simply enough, the way I set it up is during the waiting period I equip the grenades so when I scroll up the next weapon will be the chainsaw. I run past lance, quickly scroll up, hold mouse button and just walk into lance until he dies.

When the lance cutscene finishes, you have a minute to kill lance and get back to the top of the stairs. What I do is after I kill lance, I shoot the guys who spawn with lance and then move to the right of the door at the top of the stairs. Equip the M60 and right click and just shoot the guys as they come towards you. This is the safest set up for sonny spawn that I know of, I have yet to fail doing this.

This all can be seen here (with input display as well): youtu.be/mA81vwDcU7M?t=3459 (sorry about the link, you're gonna have to copy and paste as speedrun.com doesn't go the timestamp)