Q1: What is the best pdf merger pro for me?
There are two types of PDF merger pro to choose from: online and offline. The online PDF merger pro does not require the installation of task software, as long as you have internet access. But the offline one needs to download and install the software in order to work.
Q2: How to combine pdf on ubuntu?
It is a online pdf merger. You don't need to install the task software, and merge pdf on ubuntu, just use the browser that comes with your system.