March weather is very good. About 22-26 degrees and blue skies. You’ll be able to find and photograph kangaroos.

Well, I don't live in Perth, but July is in winter there, and the kangaroos are always on the island, so as long as it isn't raining, I think a July afternoon/evening just before sunset would be perfect.

Yes its a free entry park

Heirisson Island is an easy and pleasant walk from either side of the river. The walk from the Barrack Street Jetty is about 3km along the river. Its also great for a cycle. If you haven't walked along here, its well worth it. This time of year i would definitely take a jacket though. Another good option is to take the red CAT bus (free) to just near the WACA (West Australian Cricket Association ground) and the just take a short walk across the bridge.

Heirisson island is home to a number of Kangaroos which for a while now has been closed off to tourists due to a number of issues that occurred. Unfortunately, its a few people that spoilt it for the majority. But its important to protect the Kangaroos, so they kept the section fenced.

Catch a bus that goes over the Causeway or goes as far as the WACA cricket ground. Then you have to walk over to Heirisson Island . Careful crossing over the Causeway as pedestrian travel is hazardous there.