Keeping this in consideration, will I lose my Philippine citizenship if I become a US citizen?
No you can not. The moment you were naturalized as a US citizen, you have relinquished all your rights and privileges as a Philippine citizen, which includes the possession of a Philippine passport. As such, your Philippine passport is no longer valid.
Beside above, can a foreigner apply for dual citizenship in the Philippines? Thus, foreigners and those who acquired Philippine citizenship through naturalization cannot apply under this law but can apply for naturalization as a Filipino Citizen under the following laws: Commonwealth Act No.
Similarly one may ask, does Philippines offer dual citizenship?
Only natural-born citizens of the Philippines who have become citizens of another country by reason of naturalization may retain or re-acquire their Philippine citizenship under this Act. Application for Dual Citizenship is made in person and by appointment only. The Consulate does not accept mailed-in applications.
Can a US citizen live permanently in the Philippines?
Yes, under the Philippine Immigration Act of 1940, Section 13 (a) you are eligible for permanent residency in the Philippines. This visa is issued to an alien on the basis of his valid marriage to a Philippine citizen. He was allowed entry into the Philippines and was authorized by Immigration authorities to stay.