TIFF is only the best format for poster print if you are printing a photograph or some other raster image e.g. an image straight from Photoshop. Converting to TIFF would rasterise text unnecessarily, which is bad for print quality (or at best at very high resolutions, neutral).
You'd be better off either:
I'd recommend the former if you need to edit or set specifications in the PDF before printing, like setting colour profiles or bleed. I'd recommend the latter for simplicity if you don't need any of that or don't know what any of that means :-). Don't forget that unlike some of what you link to, if you're printing the posters yourself, you've got control over the software, settings etc.
Make sure that any raster images in what will become the print version of the page are high resolution (usually 300 PPI), and be aware of the difference between RGB and CMYK colours - else you might get disappointingly washed out looking colours, particularly pure reds, blues and greens.
For web fonts:
- If you use the former option, it'll vary from software to software, but you'll definitely be able to use web fonts if you also have the font installed on the machine you're printing from. If that's not an option, look for a converter that has a feature to embed web fonts in the PDF - this question might be relevant - (and be aware that there might be legal licensing issues about this since serving / being served fonts and embedding fonts are usually coverred by different types of licence - though if you only use the PDF to print and never distribute the PDF you might be okay).
- For the latter, you just need to make sure you're printing from an up-to-date browser that can print web fonts. According to this thread most browsers can cope, and since you're doing the printing, you can just make sure you use a browser that works.