Thanks for all the kind words guys! I'll attempt to answer the questions individually here.
Do you know if you can add static grass to this type of mat?
Honestly I have no idea. Sorry but I've never used static grass before

if anyone knows, please let us know! My concern is that it'll lay down once its rolled up. I had thought about added small patches of teddy bear fur as grass tufts and may still do that in the future.
What exactly is a drop cloth? Is it some sort of canvas?
I think you have the right idea now. Yeah it's a cloth that you lay on the floor while painting. I just used that because it was cheap and roughly the same size and was easily located in the paint department. You could also get some canvas from a fabric store.
This is a good time to note something about the fabric. This mat is fairly heavy and does not look very good with hills placed under it. Felt would probably work better if you wanted to have a mat to place hills and stuff under because its a bit more flexible and would conform easier.
Which flock did you use - the fine turf or the blended turf?
Fine terf. I just like working with it.
For the OP - did you use all 4 tubes of caulking for your mat?
Sorry I forgot to mention this! No I only used 2 tubes. I just got a good thin coat of coverage. I thought about using another tube just for some more bumps and undulations but decides to not worry about it this time.
That is absolutely stunning! It looks fantastic! Have fun on it, and get some pictures while you do.
Jevenkah
Thanks and I will!