Need to know a make, model, and description of the stamps. The British used more than one service rifle during that time.
50-300 or so
Nothing more than face value - unless there's something that makes it unique.
50-150 or so
Ive seen them fo £30 to £40
There are many ways one can learn the value of stamps from Japan. One can learn the value of stamps from Japan at popular on the web sources such as Baxley Stamps and Herrick Stamps.
100-1000 USD depending on specifics
50-500
The value of British stamps issued in 2000 varies depending on factors such as condition, rarity, and demand among collectors. Generally, most standard stamps from that year are valued at or near their face value, while commemorative issues can be worth more, especially if they are in mint condition. For a precise valuation, it's best to consult a stamp catalog or a professional appraiser.
50-500 USD depending on condition, variation, accessories, etc..
50-150 USD or so
Value entirely depends on what stamps are in the album. Without knowing what stamps, country and condition, it's impossible to value.
Assuming you mean a British MILITARY rifle, such as the SMLE, between $100-$350, depending on condition and originality. Rifles that have been "sporterized" lose much of their value as a collector's item.