No, these are entirely different beverages produced in very different ways.
Dry vermouth will last longer if it is refrigerated. Vermouth is a wine (lower in alcohol than port). The flavour tends to change within a few months. It is also available in half bottles or mini bottles in some places. These are better unless you are using a lot of vermouth.
Yes it is similar, and should produce a nice result. It's not the same though... You could also try white wine.A lot would also depend on the meat you are using. You could use Calvados for pork, or brandy for beef. I do not believe Vermouth , which is matured through herbs is in any way the same as sherry, you would definitely be better off with white wine.
Vermouth is a white wine. It is a drug, in the sense that it can induce unconsciousness.
A dry white can be used in place of vermouth.
PCH answer : Barley Vermouth is made from White Wine flavoured with herbs and spices (not barley)
No
Noilly Prat is the top selling dry vermouth in the world. It is a very high quality product. Dolin is another very good dry vermouth. When Ian Fleming wrote Casino Royale, ,he substituted a French aperitif wine called Lillet for the vermouth. Lillet is a dry wine with bitters and orange with hints of oak.
Port is a type of fortified wine. It's sweeter and has a higher alcohol content than most wines.
Vermouth
There are over sixty botanicals that may be used in making vermouth, though most brands of vermouth use somewhere between a dozen or two dozen. Some of the most common are orange and lemon peel, wormwood (from with vermouth gets its name), chamomile, lavender, rose petals, cloves. You can find more information in The Mixellany Guide to Vermouth by Anistatia Miller and Jared Brown (Mixellany Limited, 2011, www.mixellany.com). It is the first comprehensive book devoted to vermouth.
Vermouth is either a white or red wine that has been flavored with herbs.
50mL is the correct measure for port - its a FORTIFIED wine. Same measure for sherry.