Isaac Hollis & Sons were noted British gunmakers from c.1860-1900. They made many top quality shotguns and rifles with many levels of ornamentation. This is one that should be individually hands-on appraised. sales@countrygunsmith.net
Hammerless
They probably denote what choke the barrel has.
Information on this weapon can be found at any reputable gun dealer. And any bookstore will have catalogs on old or new firearms.
Rifle, handgun and shotgun can all have "long" barrels
The cartridges will pop out.
I would look at the number of barrels. If there is more than one barrel, you know you have at least a double barrel shotgun. If there are 1 or less barrels, then you don't.
Yes, the barrel on a Remington Model 48 shotgun does move back into the loading chamber when fired. This movement is part of the semi-automatic cycling action of the shotgun.
That would depend on the make and model of the shotgun in question,and the length of the barrel/barrels that came with the shotgun.
With the serial number that you provided,your Ithaca double barrel shotgun with the damascus barrels was produced in the year 1900.
No published history on the company.
100-300 USD
If you're lucky about £400.00