making wiring harness from scratch

Ok couple questions while I stock up supplies.
1. I have a good selection of 14 gauge wire. Is it ok to sub this in where the 16 gauge is called for? Bigger is better, but I wasnt sure how much more "awkward" it would make the harness? Also I believe most connectors are the same size 14 vs 16?
Question 2. What are the open ended connectors called in dash? Pic attached
Thanks
Steve

20200122_135851.jpg