custom post types search

hello my site its http://www.buscadordempleos.com/trabajos

a-i would like to know, is it possible to use this plugin only for custom post types?
my site work with wp job manager (use custom post types “jobs”)

b-do you need if this plugin can help me to improvee the search results speed?

c-do you know if i can put as dropdown or check box box like categories, tags, etc?
thanks

https://wordpress.org/plugins/relevanssi/