You can download AZImage from its home page - see related links.
For example to upload to Google Picasa you can either use Google Picasa or other tools supporting it (like AZImage).
You can use AZImage to upload the photos. The photos will first upload into an album called "AZImage Photos" and are not visible to anyone. After that you can go on an approve the photos and select who is allowed to see them.See related links for more details. They have a demo video linked on their page to get a preview of how it works before downloading and installing everything.
Try AZImage - see reference. The tool can resize and upload the photos for you.They have on their webpage some video tutorials, this may help you out to find if the tool fits your needs.
You should look either for a dedicated gif editor or for image editing programs like GIMP, Photoshop. If you only want to convert to gif, an image converter like AZImage will work just fine.
You cannot calculate it, since it depends on some varying factors like the image content and some other JPEG parameters like optimization or progressive. You can use a program, e.g. AZImage - see links -, that allows you to fine set the compression parameters to get an idea about the resulting size.
Try AZImage - see reference. The tool can resize and upload the photos for you.Also, look if there is a limit of 100 pictures per WEB Album. I do not know anything about that.
You can, if this photo is saved in GIF for example (or any other format that does not use any variable compression). In this case simply reduce the output image size until you get the 200kb. If you save it into JPEG you have to reduce the size so that with average JPEG it is a little bit lower than 200kb, than slowly increase the quality of the JPEG until you reach 200kb. It is hard and there is no quarantee that you will land exactly on 200kb. It may be few kB more or less. Try using AZImage - see reference. It is a simple to use tool that provides also the advanced features you need. To have a quick preview search on youtube.com after "resize azimage".
Try AZImage, see reference. I cannot guarantee that it will work, but I succeeded converting some pretty huge RAW files with the tool.Leave me please a feedback, I am interesed if you can do it.
You can use the Java interface or third party tools like iPhoto or AZImage to upload more than 5 images to an album.The Java interface (from Facebook) - there are some problems related to the high compression that ruins the image quality.iPhoto - ... need detail, I do not use this tool.AZImage - see related link.
The size of a JPEG file depends on the compression algorithm and on the content of the source image. There is no direct answer to you question. What you can do to find it out is to capture the screen, then use mspaint to save the file as a bitmap and after that convert the bitmap to a jpeg using an image converter that allows you to play with the jpeg parameters - for example AZImage. See also related questions and links.
Basically you have to reduce the size of the photo 1.58 times on both x and y axis. This way you achive a reduction of 1.58^2 = 2.5 and the image will have about 2 mp.You can use any image converter and enter a percentage of 100% / 1.58 = 63% (Paint is a example - but the image quality is not very good, AZImage is another possibility, GIMP, Photoshop, ...)
There are some image viewers that are able to do that, but that depends on the image type and software implementation. A VERY large image (one that does not fit in the computer memory) will probably fail to open with 99,99% of the software. The best way is to convert it to a smaller image - some image converters support line based processing or similar. If it is a RAW image give it a try to with a software that loads the jpeg previews directly (without conversion). For example AZImage in the preview window.