Welcome to the forum.
First, I always use .PSD's (when Save_As from PS, and PSE is the same), as it easily includes Transparency. TIFF supports Transparency, but I find that .PSD's cannot be beaten. You will want to Import your still graphic into the Project (think you've done this), and then just drag that graphic to an upper Video Track, say Video Track 2, when your Clips are on Video Track 1. This will Import with the Duration set in Edit>Preferences>General, but it does not really matter for just one, or a few, as you can click-drag on the Tail to extend the Duration, as is required.
To do graphics in PS, I use the Image New Presets that match my Project, say NTSC DV 720 x 480 4:3 (Standard) w/ Guides. I do not know if PSE has those Presets, like PS does, but you will do best to do all Scaling in PSE, rather than letting PrE do it for you - quality will be better.
Good luck, and hope that helps,
The animation is easily accomplished in PrE, with the use of Keyframes on the fixed Effects>Motion>Scale and Motion>Position. You can also Keyframe many other Effects, such as Blur, etc. If you are new to the concept of Keyframes, I strongly recommend Steve Grisetti's Learning Series on Muvipix. Once one has the concepts down, it will become easy. I have some bookmarked tutorials, but those are for Premiere, or PrPro, and not for PrE. The concept is the same, but the controls and some of the locations are different. Steve's tutorials are as good as it gets, and he goes into much more detail in his books, one of which is for both PrE & PSE, though that one might not have been updated to PrE/PSE 8, as my copy is for version 7.
Now, and I do not know about PrE and PSE, but I do my graphics as Layers (PSD's retain that, if desired), and Import as a Sequence into PrPro. This allows me to Keyframe animate every possible aspect. I can say, have the border (Stroke) fly in from one direction, as the graphic's background (Fill) flies in from another, and then the various elements of Type can be animated too. As PrE does not have Sequences, I doubt that it will handle the animation of Layers, at least not that I know of, without doing separate graphics for each element.