Well, ok, for starters,
AI files:
You need to save them with a PDF Compatible file, if you want the data to be previewed in your InDesign document, and for exporting to InDesign. When you save an AI file you get an option to Include a Compatible PDF. This is standard for AI, there is no need to create a PDF from the AI file.
As for file size regarding your PDF for screen.
The Illustrator file, depending on if it is Vector Dense then there is no real way that InDesign can reduce the size of the file, thus resulting in a large file.
There are two ways around this, export your AI files to JPG and then have them about 150dpi. Or in InDesign, Edit>Transparancy Flattener>Preset and make a new preset, then move the slider all the way to the left, but not at 0 at 1, that way it Rasterizes everything but the text.
When you create your PDF you can select this Transparecny Preset, but it has to be Acrobat 4 Compatible to select this.
You should really make a copy of all your work that you want to show off and put it into one big folder.
Open all the files of the same file type.
If it's illustrator, you could export to JPEG or do the transparency flattener trick in InDesign.
All your photoshop files, you should save as Jpeg at 150dpi.
You can just place PDF's into InDesign, that won't cause any problems, but you might want to consider the transparency flattner trick (described above) to reduce the vector dense files.
People may say that vector is a smaller file size than raster, but not all the time, this is why I say Vector Dense, I have Illy files that are 50-100 mb in size.
When you export to PDF from InDesign your settings should be similar to this.
General:
Adobe PDF Preset: Smallest File Size (this will change to modified after you make a few changes)
Standard None, Compatability Acrobat 4
Compression:
Bicubic Downsampling to: 150 pixels per inch
For images above: 150 pixels per inch
Compression: Automatic
Image Quality: Medium
You can leave the rest alone if you wish.
Marks and Bleeds:
Leave alone.
Output:
Colour Conversion: Convert to Destination
Destination: Apple RGB
Profile Inclusion Policy: Don't Include
Ink Manager:
Map All Colours to CMYK, unless you want to show spots in teh PDF.
Advanced:
Leave unchanged.
And that's it.
You should get a good, relatively low PDF from this that is viewable on screen.
If you don't, change the Image Resolution in the Compression to 100 ppi. But it should be low enough.
The reason I say to open all to duplicate all the files and resize them in photoshop to 150dpi is because they make smaller thumbnails for InDesign.
You can turn off the Preview Images in InDesign
Edit>Preferences>Saving InDesign Files, uncheck the Always Save a Preview Image with Documents.
This reduces the size of the PDF too.
