Re: number 1, I should have clarified–yes, I was in an HDHP throughout 2017 and will be throughout 2017 (God willing and the creeks don’t rise, as my grandma used to say). It’s an individual plan (i.e., not through my employer) that also covers family members (two of my kids).
Re: number 2, I will look at Fidelity.
Re: number 3, I am confused. My employer doesn’t and won’t be contributing anything to my HSA. This is an account I will be opening on my own using my net pay. All the contributions will come from me. Based on earlier responses, it doesn’t appear that my employer can direct-deposit to my HSA and deduct from my paycheck the contribution pre-tax (and, hence, pre-FICA), so the only up-front tax advantage I will get is as a deduction to my gross income (I believe on line 25 of my 1040, completing Form 8889). This is still advantageous–if I contribute the maximum, at my income level, I will save 24% of $6,750, or $1620 in federal income tax. So even though I don’t get the FICA savings on that $6,750 (a little over $500), something is better than nothing.
Thanks again for your help in answering my question and providing additional information for those who may have employer-based HSAs. The caveats in your last paragraph are well-advised.