So all these three questions have something to do with stress.
The more stressed you are, the harder it is to go into trance, but also, to stay there.
The last question shows you immediately how a stress spike - getting scared or even just surprised - will immediately bounce you out of trance and meditation; and the first question, about startling out of trance at the slightest noise, tells us also right away that the person was stressed already.
The middle question points out that it's not just general stress that's the problem, but often "what's on your mind" at the time - that which stresses you out the most in your life at the time is most likely to interrupt meditation, trance, and getting into Sanctuary because your mind "flips back" to those topics under stress.
Stress and meditation are mutually exclusive (I actually wrote an article on the topic once, see here) and in order to meditate successfully or go into trance, never mind into a stable, deep and lucid trance which is what with PS, we need to take out stress.
There are basically two ways to do this.
The first is to take on your stress and do something with it, so it's out of the way and the path into trance is clear.
For example, Robert Monroe used to suggest as the very first thing in his inductions to walk on a beach and find a big old heavy chest with a very heavy lid. Into that, you place the things that stress you until they're all inside. Then you close the heavy lid, turn away and walk into the meditation or trance from there.
Our version of this is the Thought Flow technique, whereby you hold out your hands and create a sphere into which you pour your troubles and all that worries you. Then, when the sphere has absorbed everything you need to get rid of, you lift it up and throw it backwards over your head so it's gone. This has the added bonus of the problems being handed over to the HEROS (higher energetic reality operating systems) for further processing.
Another version is to have your troubles become encased in bubbles that float away, or even bubble up from out of the very structure of your body, as in the Bubble induction.
In true Project Sanctuary style, you might ask for the perfect place in time and space that would take your troubles successfully and do something with them, evolve them, whilst you do something else in meditation and rest, go into trance, explore the Sanctuary worlds.
This "does something about" those things that stress you and makes a wonderful entry into trance.
The other option you have for significantly improving meditation results and achieve much, MUCH deeper and more profound trance states is to use "inductions within inductions".
This means instead of going to just one place and trying to stay there, you go to a succession of places that like step stones lead you deeper and deeper into the trance or meditation, or let you go higher and higher, if you prefer that metaphor of soaring consciousness as I do.
For example, you can start your meditation by going to a wonderful place where delicious healing beings massage you until you feel better, and then set out into the meditation.
You might choose to go somewhere for a spot of gladiatorial combat first to get rid of your stress, or put in some exertion fighting your way through a jungle with a machete, and letting your energy mind choose how long that has to go on for until you're ready to find the clearing and the path forward into the meditation.
With the induction loops, there is no need to limit yourself to just two, you can have many more than that.
A really good example is the HypnoSleep spiral pattern, which is also good practice for you to learn just how many habitats you can shift and sleep in before things become so abstract that your conscious mind can't keep up any longer. For successful meditation, deep trance states and extremely powerful LUCID trance states, you want to stop before you fall asleep or go unconscious, and using a progression of habitats repeatedly can teach you when and were that happens. It can also help your consciousness expand its ability to stay awake over time and get higher, further, deeper as it learns.
A combination of active stress relief pre-meditations and induction loops, according to what you need at the time, will significantly enhance your abilities with meditation and also improve your clarity and focus too.
One last tip.
If you keep bouncing out at the very beginning, accept that, don't get distraught, and say to yourself, say out aloud, "Ok, so where were we? Last thing I remember was that I was flying over this mountain, and the sun was just about to set in the west, and I could see a river ..."
This will take you back to where you were. You can repeat this as many times as you need and until you find yourself settling into the meditation, relaxing, and that reality taking over completely until you have a resonant, clear, lucid trance which is a marvellous experience and so restful and healthy for mind, body and spirit alike.