1) Yes. Macrium leads you through the process very well as do some of the other products. You just need to take your time and ensure that you understand the choices being offered at any given step. Read the procedures before hand. Lots of online tutorials regarding cloning "how-to's".
2) No - if all goes well the SSD will be just the same as the HDD. Unplug HDD, plug in SSD. (Presumption that both are SATA connections.)
3) May provide recovery software and various utilities. I.e. the disc may be (should be) bootable if the existing HDD is not booting. The idea being to get the system running again if the problem is software related. And will circumvent some hardware failures by just using the basic built in drivers and devices.
4) A clean install would not include your data - only the operating system. No data, no applications, no third party hardware drivers. Everything else would need to be reloaded/downloaded and reinstalled. Then configured. I back up to clones but also do data backups per se with respect to certain directories and files. Plus an image or two every few weeks.
Always trade-offs and I tend to be conservative and have multiple recovery options. I do not download movies, books,etc. and have minimal data saved - mostly family photographs. Multiple copies on different media everywhere - excluding the web/cloud.