Weather in March/April

Hi,
I was wondering due to the weather if it is not advisable to go to Samoa at all? The flights and everything is really cheap. Can someone explain what a usual day is like? Does the sun not come out at all? Does it rain all day long? Storms?

Also, how long is the ferry ride from Upolu to Savaii? Is it rough? Is there a plane? How much does that cost?
What is the best/ cheapest car rental company in Upolu?

I have 5 days in Upolu, what do you think I must see??

So many questions...thank you so much!

Hi We are just back from Samoa and although it did rain most days it never was enough to stop us doing what we wanted.
Plenty of sun and hot weather so you dried out if you did get wet anyway.
I think the ferry ride between Upolu and Savaii is about 90 minutes and it can be rough, we flew.
The rental companies all charge much the same rates, just get a vehicle that is in good condition.
Around Apia the Robert Louis Stevenson museum and the hike up to his grave is interesting if you are fit.
The Tombs and Memorials out on the peninsula interested us as did visits to the food market etc.
Around Upolu there are plenty of churches, beaches, waterfalls etc to see, same on Savaii plus the blowholes.
Must see items just depend on what interests you.
We really like Samoa and have not had any problems with dogs despite what other TT'rs may say.

At least from May to September the weather is usually quite nice with lots of sunshine (Dry Season). Occasional rain is possible and very much needed. October to April is more wet but hardly more than one real rainy day at a time.

No more flights between the islands!! The service is cancelled now.

The ferry ride takes 60 minutes on the big ship, 90 minutes on the smaller one. The bigger Lady Samoa II leaves Mulifanua (Upolu) at 8am, 12 pm and 4pm, Salelologa (Savaii) at 6am, 10am, 2 pm. The small boat goes at the same times, reversed ports.
The ride is usually quite smooth during the Dry Season (see above) and on the Lady Samoa II anyway.
Costs are 9 Tala (approx. 3.40 USD) per person each way. For a standard vehicle they charge 65 Tala (approx. 25 USD) each way (driver included).

Car rental companies have all the same rates, as 1. said. Quality of car is the only difference, some are really a bit worn out already.