Are there any advertising rules that would govern typical trust products/services other than NDIP rules, member FDIC rules, etc?

The only hard and fast rule, I can think of is the prohibition on advertising Common Trust Funds (National Bank prohibition see 12 CFR 9.18(a)1.). As for advertising or marketing other Trusts products and services, so long as you are not advertising that you offer legal, tax, or accounting advice when you really aren't, I can't think of any limitations.

Also, be cautious about promoting the FDIC Insurance coverage. Be sure, you understand how FDIC insurance coverage applies to a trust account and how much of an account is insured.