Wordpress already have the post count option when u add the Categories widget.
u will be looking at css. heres some nice tuts to get started https://codepen.io/tag/glowing%20text/
run your site with tools.pingdom.com.
U find the suggestions needed to make your site quicker.
Basically for speed optimize on shared hosting, there are available free plugins –
1) use page cache plugin
2) image lossless compression
3) use Jetpack photon
hope that gives u some direction
