Great questions, turtledude, I look forward to our conversations on this site.
I like turtles
Glad you joined us!
Here are my interpretations, which might include misunderstandings. Please take anything useful and set the rest aside.
As I see it, service to others means seeking to use our lives to help others experience freedom from suffering, to get to have happiness and spiritual growth.
This occurs when we are open hearted and welcome "green ray" energy to flow through us. Empathy and compassion lead us to seek to understand the other person's point of view, and to help them.
In the positive loving path, a key threshold is when we live this way more than half the time. As Carla Rueckert describes it in one of her commentaries, suppose you could share your sandwich with someone who is hungry. If you naturally do this half the time, you are over this threshold.
A person who reaches this threshold has learned how to make their Choice, therefore can move on from third density to higher levels of learning and growth.
It is also possible to be harvested on the negative side, which means less than 5% of one's focus is on kindly loving one's neighbor.
In either case, harvest is not necessarily a conscious choice. It is a total combination of mind/body/spirit entity's entire identity and willpower. Harvest is not an interview, like a job or co-op board, but our spiritual response to the amount of loving Light we can use. The ability to use this Light comes from having open, balanced, unblocked chakras.
Between these extremes is "the sinkhole of indifference." It is as hard to polarize either way. That means that it comes easily to most people to be kind and loving about 1/4 of the time. They need to either double their positivity to be eligible for positive harvest, or else cut their positivity to a tiny fraction of average to qualify for negative harvest. If they don't do either this lifetime, they will get another 3rd density lifetime to try again at making the Choice.
Spiritual seekers on either polarity can study how to apply spiritual techniques in their physical lives. They can also study how to apply spiritual techniques in spiritual realms. As I see it, all of these studies together are "the work of the adept." Either positive or negative spiritual "magic" would be of no interest to someone in the sinkhole.
Advanced adepts may make their own choice to exit 3rd density, but for most people they need to wait for a Harvest time to occur. If they miss the current opportunity, they'll have to go through another 25,000 year cycle.
As for your philosophy question:
If you wonder
in order to become more skillful and powerful at your choice of service orientation - to invest your life in others, or to manipulate others to serve you - then the philosophy study is a spiritual practice. Otherwise, it is just an activity that doesn't matter much, for good or ill, just like if you happen to prefer long walks with dogs or playing miniature golf.
Philosophy, dog walking, and mini-golf can all be enjoyable pasttimes of loving sweet people and also of ruthless psychopaths. So the activity itself doesn't really matter. What matters is why you do the activity and what it changes in your life.