Yes its best to resize to 1280 wide although you can go smaller, I used to do 1024 in the past. This makes the images between 200k and 400k. We do have plenty of space on the website.
We found it best to upload under 100 photos at a time, although more does work.
Click on Gallery Drop Down and choose Add Album
Fill in the Title, Description and Keywords then click Save Changes
The next page then gives you Upload Pictures and Edit Album button. Click on Upload Pictures
This opens the manage attachments window with an Add File button on the right, click on Add Files and the Select Files
Choose the files from your computer and click 'Open', the files appear in a list, then click on 'Upload Files' and they start uploading.
Once complete, you can click on ;'Done' on the manage attachments window, and then you see thumbnails of all the images you have uploaded, where you can edit captions if you desire.
Once done click on save changes, now all your images re saved in the album.