Means it was made in February 1942. See related links.
Which ones? The barrel? That's a date code. Check Remington Society of America - manufactured date link.
Doesn't mean anything other then it's a model 1100.The serial won't help you unless you call Remington but It's date stamped on the barrel. Check the Remington Society of America's manufactured date link for details.
It's November 1941 or 1963 depending on if it's fairly low serial or a very high one, that date is either third year or last year production.
Markings typically include model, The Remington trademark, date of manufacture, test marks, inspectors, and proof mark. In some cases it may be a factory repair mark, or indication of Magnaflux testing. See the link below for an illustration of barrel code markings. Note these are for REMINGTON only.
According to all of the Remington date code decoders I have found, your rifle was manufactured in Feb 1946. See http://rimfirecentral.com/forums/showthread.php?t=9555 for reference to the chart. Hope this helps!
The ones on the left side of the barrel by receiver are the date of manufacture code see related links for information on the Remington Society of America.
i don't actually see the answer to edit but there is not "significance" in the serial or meaning it's just a serial. There's a prefix on the model 700's starting in later half of the 70's do to the date code rolling over but other then that Remington doesn't put an meanings in them.
I think you mean a Model 12 RIFLE, have tables for serial but I can't post all that or if it's made after 1920 somewhere after serial 572,000 it's date code stamped on the barrel with month and year. See related links to a pointer to a table on the Remington Society of America.
The 1100 designation for a Remington shotgun is the model number. Remington makes the 1100 model in a trap version and a field version.
If you don't know the model then it's probably not marked which would mean it's a model 14. They were made from 1914 to early 1930's, If it's before around 85,000 serial number would need it to date after that it will be date code stamped on the barrel, see related links to get details.
Classic Deluxe
It's a model designation that Remington uses, i.e., Remington 11-87.