Yea not sure how that RTV will hold up without compression. Maybe RTV and a hose clamp, wide one, at best this would be temporary if it even works.

As long as you weren't smoking, white, I think you just have an issue with the coolant leaking, and that's it.

I would replace the T-stat, upper rad hose, and any other hoses you see in bad shape, in one shot. Then see if you expansion tank is leaking. Search for some DIYs and do it yourself. Lots of good info here. Will be cheaper and done right, hopefully.