W.S.
I think, Yes, provided, brand is same in both cases, when you are drawing the comparison, like AGS Maintenance battery Vs AGS Lead Acid battery.
You may start the car after every 3-4 days, to be on a safer side.
Yes, especially when normal air is filled (If Nitrogen is filled, then tyres may not loose air, especially that frequently, unless / until tyre has got some puncture(s)).
It depends on you. If you would like to have one with you, and check air pressure, then there is no harm in having one.
A good one might cost somewhere around 750-1500 Rs.
Following link from Pakwheels Auto Store might help:
https://www.pakwheels.com/accessories-spare-parts/tyre-pressure-guage/213232
You may also check Daraz website to get idea regarding products and prices.
It depends on your convenience. If you want to install it, get it installed, otherwise, if you think that it is not that important and you can manage without it, then you may leave it.
3500-4000 Kms / 06 months, whichever comes first.
10w-40, 15w-40, 20w-50 are mostly deployed in Mehran. Since you have not mentioned the model year, odometer reading of your car, and oil which is currently being poured, I regret that fellow members may not be able to guide precisely.
10,000 Kms I would say.
I hope, all above helps. Thank you.