This is a very interesting question.
Actually there is no mention, question or needed declaration concerning any restrictions on absences from UK until such time that your application is made for British Citizenship.
When application is made for British Citizenship you'll need to satisfy the residence requirement. These restrictions do go back a few years so it makes sense to count back from the time you plan to apply according to the regulation.
If you apply for citizenship as the spouse or civil partner of a British Citizen the countback is 3 years, and the total of absence for the whole 3 year period should not exceed 270 days.
Additionally though, you should not have been absent for more than 90 days in the 12 months period immediately preceding your application.
Based on a 5 year countback period the total absence restriction during the whole period is then 450 days, again with a limit of 90 days in the final 12 month period.
If you do the math then it works out at an average of 90 days per year for either scenario.
If in one of those qualifying years you spend say 100 days absence outside of UK then you'll need to limit another qualifying year to 80 days in order to stay on target.
So you only really to control the absences within the countback period needed for British Citizen application.
Concerning your questions relating to passport name changes I really can't offer any time scales for this in Philippines.
Usually, you will be able to retain your 'old' passport you wouldn't need to re-establish your visa in your new passport.
The visa would remain valid, but you'd need to carry both passports at all times and show to the immigration officer upon arrival to UK
Anyone with permission for 'limited leave' to remain in UK (eg Spouse visa) needs to actually be in the UK before application can be made for what is called 'transfer of conditions' (TOC)
Please be aware that there's a whopping transfer charge of £220