Need help for poplar barn siding

Hi, The barn was finished about 6 months ago.

1. Poplar exterior siding. We live in Austin, TX. The siding is starting to bleach out and gray (except under the lean-to). I NEED UV PROTECTION!!! Here is my prioritized list of qualities of the ideal product:
- superior UV protection
- long lasting
- water repelling
- water based
- makes the wood the same color it is when it is wet (very pretty)
- not a shiny finish

2. Pine T&G inside walls and stall fronts
They have been sanded to a medium grit. Qualities I prefer:
- water and scuff resistant
- long lasting
- water based
- clear finish
- not a shiny finish

I appreciate any suggestions you have. I don't care how many coats I have to put on up front, just gonna be hard to do more work to it down the road once we have the critters moved in.