should i create new iCloud account after married?

You can create a new iCloud.com account, but it will be 100% seperate from your original Apple ID you have been using. You will never be able to merge them either, so you will always have 2 accounts.

If you have had the current Apple ID for a long while, I would just make an alias and change you name at appleid.apple.com You can also change how your name appears when you send an email. On an iOS device you will go to Settings > Mail, Contacts, Calendars > Tap on your iCloud Account > Tap on the Account Name (the email) > Tap on Mail > Change how you want your name to appear on outgoing emails.

To answer your second question, you can have multiple accounts on your Macbook or iOS device. Your primary iCloud account should be placed in System Preferences > iCloud and the others should be listed in System Preferences > Internet Accounts. This is similar on the iOS devices: Primary iCloud goes in Settings > iCloud and the others should be added in Settings > Mail, Contacts, Calendars.

Note: You will see the primary account in internet accounts/mail, contacts, calendars as well once it's logged in (this is normal).

It's entirely up to you. If you create a new account you can choose a new @icloud.com email address to go with it. You can also migrate your existing iCloud data to the new account, which is fairly easy to do if you have an iOS device. You could add the existing account as a secondary account on your devices/Mac, but once the data is migrated to the new account, there wouldn't be a need to do so unless you wanted to continue to access your existing iCloud email account.

If you want to migrate your data to a new account using an iOS device, start by saving any photo stream photos that you want to keep to your camera roll (unless already there) by opening your my photo stream album, tapping Select, tapping the photos, tap the share icon (box with upward facing arrow), then tapping Save to Camera Roll. If you are syncing notes with iCloud that you want to keep, you'll need to open each of your notes and email them to yourself so you can later copy and paste the text into new notes created in your new account. Then go to Settings>iCloud, tap Delete Account (which only deletes it from this device, not from iCloud), provide the password to turn off Find My iDevice and choose Keep on My iDevice when prompted . Then sign back in with a different Apple ID to create your new account and choose Merge to upload your data. When you turn Mail on you can choose your new email address. (Type carefully because once created, it cannot be changed.) You can then set up mail forwarding from your old address to your new one on icloud.com.

Then on your Mac, go to System Preferences>iCloud, click Sign Out, choose Delete at all of the prompts, then sign back in with your new ID. If you still want to access your old account, go to System Preferences>Internet Accounts>iCloud, sign in with your old account ID and check Mail.

I'm having this same issue and talked to Apple Care about it. It seems like there is no fix at this time, but hopefully they will come out with a merge feature or allow you to change your icloud email in the future.