Here's the relevant sections of the contract.
Chap. 8. A. 4. b. A class of service higher than coach shall be authorized if:
i. a deadhead exceeds 5 scheduled block hours;
Chap. 8. C. 1. g. Mid-Trip Deviations
A pilot may deviate from a scheduled deadhead between any two revenue segments of a trip only with the prior approval of his ACP, or his designee.
All approved SFS mid-trip deviations that were scheduled on the airbridge, require the pilot to inform SFS GOC not later than 24 hours prior to the scheduled airbridge departure, so that the seat reservations may be canceled.
Intent: Scheduled mid trip deadheads are included in a pilot’s deviation bank like any other deadheads.
Chap. 8. C. 2. Deadhead Deviation Banks
a. A pilot shall have a deviation bank established for each bid period. The
value of the deviation bank shall equal the value of the scheduled
deadhead tickets for trips flown during the bid period.
Chap. 8. 3. d. ii. (b) A pilot who deviates from international deadhead travel may expense hotel(s) as part of his deviation travel as follows:
(1) he may expense 1 hotel room as a deviation expense, or
(2) he may expense up to the same number of hotel rooms as in
his scheduled deadhead.
Chap. 8. 3. d. iii. (b) When hotel use is an allowable/reimbursable deviation expense:
(1) the pilot is responsible for his hotel reservation,
(2) reimbursement shall be limited to the contract hotel rate for
the city associated with the revenue portion of the trip, and
(3) authorized expenses shall not be direct billed.
So, yes, if the scheduled D/H's total combined block exceeds 5 hours then you are entitled to a higher class of service (although, if you're including the airbridge as part of the 5 hours, you might need to check with the folks in crew travel audit to confirm that's allowed).
And yes, you can use your bank to pay for a hotel if you arrive early on a mid-trip deviation.
Just be careful to cancel the airbridge at least 24 hours prior, don't direct bill the hotel, don't expect the company to pay for the internet when deviating, and be sure you understand the company will only reimburse for the room rate of the scheduled revenue hotel you were supposed to be in (Subic, if you are leaving there early).