I don't fully understand what you're planning to do but remember that any surface sector in your RTW ticket uses up one the max allowed 16 segments.
A minimum of 3 and maximum of 16 segments, including surface segments between any 2 airports, are permitted for the entire journey.
Yes, although origin-destination surface segments (where permitted by the fare rules) don't count against the 16 segment limit.
The poster wants to exceed the 16 segment limit and was asking about side tickets. As
Calchas explained, side tickets still count against the 16 segment limit, but separate tickets don't. Additional flights can be in the same PNR but ticketed separately. As long as they don't result in an additional surface segment, the RTW can still have 16 flights.