Education saving beyond 529 and ESA

Married/joint, AGI varies $150K-$220K, working spouse fully funds 401(k) and Roth IRA when qualified, non-working spouse fully funds deductible IRA when qualified. All of the above intended for our retirement, not child's education expenses.

Also saving for private K-12 and college education for our child, now 2. We have been contributing to 529 and expect these savings to primarily cover college expenses. We have also been contributing to ESA for private K-12 expenses. However, low ESA contribution limits will leave considerable gap toward fully funding private K-12 expenses and we're looking at additional (ideally, tax-advantaged) options.

We are considering an UTMA to expand our tax-advantaged savings options beyond the ESA for the private K-12 education. We will likely fund the UTMA to the extent that earnings are tax-advantaged and seek to exhaust the UTMA (and ESA) on private K-12 tuition so as not to adversely impact college financial aid opportunities.

Q1: Any comments on the soundness of this strategy; other recommendations?

Q2: Are our combined annual contributions to the 529 and UTMA limited to $22K ($11K per spouse gift tax exemption).

Also, if our income exceeds limits for ESA contributions (married/joint AGI > $190K), I understand we can simply gift $2K to our child to contribute to his ESA (which I assume must also fit within the $22K annual limit).

Q3: Are there any constraints or special considerations we need to be aware of for this gift transfer? E.g., must we actually transfer the money through our child's UTMA to substantiate the gift, or can we simply transfer the money directly from our account to the ESA and characterize this as a gift to our child direclty contributed to the ESA?

Thanks in advance for your perspectives.

Seems I may have to answer these myself...

Q1: Strategy makes sense, even although amount of possible shelter is low (since only first $1,600 of net gains tax-advantaged - child < 14yrs old). Side benefit is that the UTMA can be used to support Q3 below.

Q2: Obviously yes - 529 and UTMA contributions are both considered gifts and should fit into combined $22K gift tax exemption (although, still not certain of the implications of using the 529 5-year accelleration of gift tax exemption when combined with other gifts, e.g., gifts to the UTMA - must other gifts be < $22K and contributions to 529 be less than $55K minus other gifts?).

Q3: Custodianship of the gift must be demonstrated - e.g., via the UTMA prior to child contributing to the ESA (and again, this gifts must be considered regarding the annual gift tax exemption in years with 529 and UTMA contributions).