for UPS - higher VA, longer time before it shuts off. the typical 500-1000VA is good for around 10-15min IF ang nakakabit is yung PSU and monitor lang. siguro mga 1500-2000VA will be enough for 30min
for vacuum/blower. hindi ko gaano gets. magkaiba kasi yung dalawa. vacuum, is for sucking dirt, blower is well blowing the dirt. opposite kasi. ano ba purpose? para matanggal ang dumi? if so, then vacuum is not recommended. baka maloosen pa ang mga capacitors dahil sa pressure ng suction ng vaccum. pwede na blower (yung air compressor) BUT usually ginagawa to pag off ang computer. tanggalin ang side panels, then use the air compressor to blow off the dirt
kung gusto mo matanggal ang alikabok sa mga fan, use machine oil (i.e. singer oil). tanggalin mo ang fan, apply machine oil, ikutin ang fan until lumambot ang ikot. hindi matatanggal ang dumi sa vaccum or blower since matigas na yun so dapat tunawin muna para matanggal.
for extreme cleaning and if you can afford not to use the computer for like 3-5 days, you can wash the entire motherboard and let it dry. BUT eto ang medyo delikado dito, it HAS to be completely dry before you can put it back on. ginagawa lang to usually pag sobrang dumi na talaga. very seldom ito ginagawa and personally i have only done it two times in over 10 or so years