Hey, it's me from a month ago!
I found inserting them pretty easy, I start with them rotated forward and push them in while rotating them back (rotating the top of the CIEM towards the back of my head). Once the tip is in my ear I then rotate them slightly forward again to hook the front part near the cable under the flap of my ear.
For seal tests you can use this for a general test: http://www.sensaphonics.com/?page_id=833 It's a couple tones that test whether you have a seal by testing if you can hear the bass tone since that's what you lose first.
Also, if you lose seal you should hear it as a noticeable increase in background noise and some amount of white noise / air movement sound.
And an easy test is to rub your fingers together next to your ear, for me if I can hear any of the slight higher-pitched noise from that then I don't have a good seal.
Your CIEMs come with a cleaning tool that you can use to clean the sound tubes with; other than that just wipe them down occasionally with a damp cloth or something and you should be good.