I think, 5w-30, API SN / SN Plus, Fully Synthetic engine oil from some reputed brand would serve the purpose well. For best for bucks, you may go for Total Quartz 9000 Future series, and change oil along with genuine, OEM Oil Filter after every 5,000 Kms.
(You can also see owners / users manual of your car for more details)
ZIC, Caltex or any reputed brand would serve the purpose well.
Well, if I have to go for; I may not go for detailing, etc. (unless / otherwise it is absolutely necessary), however, car wash and wax on regular basis with interior cleaning would be best in the long run, in my humble opinion.
If you want, you can go for coating, etc. There is no harm in it, however, you will then have to maintain it, otherwise, paint will get more effected if not maintained properly.