I have a upcoming business trip that puts me in Moscow and I am taking a few days off after work finishes, going to LED for some sight seeing.

As business won't cover the personal part, I need to decide between buying LED - SVO ticket on my own versus going back to Moscow on train then going SVO

I read online and got mixed comment that

1. SU won't connect transiting bags, they don't care if you are elite or not, as long as it's not single ticket ? (will buying full flex Econ ticket on domestic leg helps?)
2. I have to exit security and enter security again when I transit in SVO?
3. How delay prone will be LED - SVO? My SVO - HKG flight won't fly until 7pm-ish so would I be safe to fly from LED around 2pm to build padding for delayed flight and baggage re-check?

Any other tips?