Hi Bruce,
Sorry for the late answer !
For your first question there is no easy way yet for you to check this on the launcher... You can use the website to have a clearer display of the asset you own ( source.substance3d.com )
And for your second question when you spend a point to buy an asset the asset will be owned by you once and for all
Meaning you won't spend another point to download it. You download it as much as you want
This is why when you click on a asset you have a contextual button : Purchase (if you don't own the asset), Download (if you already own the asset). In fact this is a way for you to know if you own the asset or not (but not that user friendly neither because you have to click on the asset you are interested in)
Let me know if you need more help on this