I think we can safely rule out death by tiger attack in Goa. Death by coconut is a posibility but there's not a lot of tigers about.
Yes, there are snakes including cobras but it you're walking on paths and have your eyes open, they shouldn't be a problem unless you go looking for one and start provoking it. Then it will become a major problem very quickly.
Mosquito's are a problem and antmalarial profalaxis is a good idea, although the number of mosquito's depends on where you're staying. Go see your local doctor before travelling as ideally, you should start taking profalaxis a couple of weeks before you visit.
Neither I nor anyone I know has ever bought a Goan rod licence. They may exist but I wouldn't worry about it to much - but if you are thinking about fishing the rivers in other states, you do need licences and the waters are policed.
Freshwater fishing in Goa is very limited. Almost all of the "rivers" that you'll find on a map or see discussed on the forum are saltwater - even if you go a long way inland.
Both boat and bank wishing are available, but you can catch plenty off the beach/bank if your timing and methods are correct.
The main predators to target are barramundi, mangrove jacks, grouper, flathead and giant trevelly - all saltwater.
As to lures, all of the above, but bring some soft plastic lures as well.
Oh, and welcome to the forum.