If you don't have your private keys you might be SOL.

I only know this guy that have good reputation if you want recovery services, his site are attached to his profile, as long as you give the hint about your password.
if you mean brute force from 0 without anything, then you need a lot of time, especially if you have long password, it can probably take a year or probably 100 years or probably more, which is impossible for now.

There's open source software available on Github: https://github.com/gurnec/btcrecover

Check the code yourself, and verify that its safe to use as I haven't looked at it for a while. But, it has worked in the past. If you aren't familiar with the software or cracking passwords that you already know parts of then you can get someone to do it who you trust. I think its Dave at walletrecoveryservices, and he has been doing it a number of years, and I've never heard anything bad.

Do note though, if you don't know any of the password, and its over a certain length it would be pointless even trying. However, if you know parts (ideally the majority) of the password then you might be in luck, and either you can find it yourself or you can contact Dave. If you think its a simple typo then most btcrecoer has that built in. Dave would likely be the person to contact if you needed this done quick as hes going to be more efficient than yourself as hes familiar with the process. 

There are number of services that can help you make your password complicated but to be the best way to protect your wallet and your device in general is to adopt 2fa authenticator

I don't know, you should write your password on paper or keep it in notepad so you don't forget. in myetherwallet, I think if I forget my password it will be a disaster because I don't know how to restore the forgotten password.

I agree to that it still depends on the complexity of the password, if it is an easy one without those special characters it will only takes weeks but if there are they will charge you more, but if the wallet has a huge amount then go for it, but since you had your private key is not possible to transfer to a new wallet.