Re: 1898 Krag
It is a U.S. Model 1898 Krag-Jorgensen rifle, but that is about all I can tell from those poor pictures. The "Krag" was the U.S. service rifle from 1892 to 1903, with three main models, 1892, 1896 and 1898. The cartridge is the .30-40 and commercial ammunition is still available.
That one does not look to be in very good condition, with most of the receiver blackening gone, and some pitting. In top shape, they go for $700-1000, but from what I can tell that one would be in the $350-400 range.
Look on the left side of the stock forward of the pistol grip and see if there is a cartouche (inspector's mark). If so, it should read JSA and a date, probably 1902.