Health & Safety now prevents the Cabin Steward from giving you any type of tablets for sea-sickness or anything else. 
Tablets can be purchased from the Pursers Office or ship`s shop. 
If these do not work, the ship`s doctor can administer an injection for a fee.
 

For safety and security reasons normally no visitors are allowed on board.
Princess Cruises have now introduced a scheme that in some ports, mostly North American, family and friends can come on board and see you off - there is a charge for this. 
They are the only cruise line re-introducing this tradition from the by-gon-era.
 

It depends on the cruise line but embarkation normally begins approximately 4 hours prior to departure.

Today's cruise ships are mostly "one class." Everyone on board can use all of the ship's facilities.

Will I get bored or feel confined?
Not likely. Most ships are a good size and it usually takes a couple of days to fully explore how many options there are on board. In addition, you get the opportunity to explore new and exciting ports of call. Cruise ships are like floating resorts and have just as many options as a fine resort. You can be by yourself lying poolside on a deck chair or you can join a dance class or sports activity. You can see a movie or play backgammon. The options are endless.
 
Cunard still have areas and lounges on board their ships that are only available to guests in their "Grill Class"

Yes, all cruise itineraries are subject to change. Guest safety is the number one priority for the cruise lines. On rare occasions, weather conditions and other unforeseen circumstances require a change in itinerary. In these situations, the cruise line staff will do everything in their power to visit an alternate port of call.