Yes Murramarang is tick-city definitely take a tick freeze spray. Avoid hanging out on any grass areas or lead litter. I haven't walked south of Durras. Depot to Pebbly beach section can't be passed around high tide safely so time it or wait it out. Merry Beach to Kioloa boat ramp, you could rock hop around the headland but much easier to zig zag the uiet streets. The property on the head is private land.
On the walk website it says contact Phil for a kayak crossing at Durras Lake. (G'day Phil

) He is the local sea kayak and tour guru.
Also there is a FB group friends of durras that post photos and could be contacted to see what the current lake opening is like.
The old walk went over Mount Durras between Pebbly and Pretty, so it could be extended a little by doing a double back loop to include this and do the new coast section again. Probably adds a decent day of walking, could leave your tent set up at pretty beach for a second night or similar.