bocadillo
Water Gypsy
What options are available for Leicester to any of the 3 Palace stations?
Nottingham Fox already gave advice on this in his OP in the Crystal Palace(Go Away) thread. That information is still current, although the availability of £13 single tickets between Leicester and Lomdon and vv is now more limited.
The best trains for the £13 tickets are the 09:35 from Leicester and the 18:55 return from St Pancras. If you want to travel at these prices though, you should book as soon as possible - the numbers are strictly limited. There are also £13 tickets left on the 17:55 return service but that could be pushing it a bit.
The £4 ticket from Kings Cross Thameslink to Norwood Junction is a Cheap Day Return. It is only valid in Zones 1-4. It must not be used to catch the faster service to East Croydon (Zone 6) and then to return to Norwood Junction. If you get caught doing this, you will be liable for a £20 penalty fare or to be reported for prosecution.
The correct route on the £4 CDR is to take a First Capital Connect train from Kings Cross Thameslink to London Bridge. Change there onto a Southern or SouthEastern service to Norwood Junction. You could alternatively take a First Capital Connect service to Tulse Hill and change there for a Southern service to Norwood Junction. By the time of your return journey the service pattern will have changed slightly - on the return journey, change at London Bridge - the trains from there to Kings Cross Thameslink leave from Platform 6.