[Plugin: NextGEN Gallery] Descriptions in Slideshow

Again, I’m new to Nextgen and WP, but most things I’ve eventually figured out with other plugins.
I cannot solve:

1) How to add the descriptions and/or alttext in my slideshow (yes, I wrote descriptions for my photos). I tried custom field on the edit page screen
Name: ngg_gal_ShowDescription
value: desc

2) Same thing with the navigation bar.
ngg_ir_ShowNavigation value =1; but it didn’t show.

3) How do I center my gallery? My vertical photos are left-justified.

4) Add background color? customizing colors/fonts? Don’t seem very straightforward.

Seems like some of these things should be on the options/parameters page for ease-of-use for new website builders. I’m sure there are many of us.
What am I missing to what looks like should be a great, functional plugin. There are features I really like – the insert image from media feature, for example.
Thanks
Andrew

https://www.ads-software.com/extend/plugins/nextgen-gallery/