First stamp definitely depicts Queen Victoria. My guess is that it is from 1890-99 (which was a definitive issue in Victoria, Australia). The Orange-Brown shade is associated with late 1890 (
http://www.stampsofvictoria.com/85-90issues.php). I have trouble seeing shades of color but if you search for "orange brown" on the web page, I think you will see your stamp. The one you have is not well centered (the margins are all different) and the perforation goes into the stamp which further reduces its value.
The second "stamp" was printed on an envelope (
http://www.ebay.co.uk/itm/like/3716...&rmvSB=true) and is not a stamp, but rather "postal stationery." I have many like this where the image was carefully cut out of the paper. Like most of my collection (and as previously discussed) these are worthless. The image is Queen Victoria and the postal stationary was issued by Great Britain. This was a common image, so it is very hard to date. The cover that is in the link is from 1896, so you know the one you have is probably from the same time period. It is hard to read the cancellation on yours, maybe 1880 or 1890 to my eyes. Since this is not a "cut square" it has less value (although less than nothing is hard to measure).
The third stamp also depicts Queen Victoria. It is from 1881 and was issued by Great Britain. To count the pearls, you have to count whole pearls (by my count, you have 16). The more valuable version has 14 pearls. There is also a version that is a different color (bluish-purple is the color I have seen described, but I am unable to see such nuances in color, so I couldn't say what the real color is). To my eye, your stamp looks light brown, but I realize that it is probably purple. If it is bluish-purple it has more value than if it is purple-violet. My gut is that if it was bluish-purple you would have had some comments right away. The stamp looks well centered left to right and not fully centered up and down, but as I understand it, this is within the "reasonable" level for a stamp of this era. The cancellation is not fancy, but it does not fully obscure the image, so this stamp should be worth the full catalog value (about 10 US cents, I think), but, practically, I think you would find it exceedingly hard to sell alone as the stamp is very common (the number I saw was 33 billion printed, that is huge amount for any stamp, so I have a feeling a couple of extra zeroes are on it, but even if the number is 33 million it would still be very common).
This is my analysis as a beginner, so please be careful with what I say. I'm doing my best to be accurate, but I am far from an expert.