Do we need a living physical Guru to learn Yoga?
Yoga is not about learning. The only part of Yoga that is learning is to learn the small steps on how to meditate properly. However, once you know the small steps, you stil need the inner doorway opened. For that part, you need a living Guru, at least once, who can open that doorway for you.
Do we need to be near the Guru Physically?
At least one physical encounter is needed. However, later progress is based on your inner ability to see the subtle realm. This subtle realm is independant of physical proximity. Here is an interesting answer given by Aurobindo when he was asked, do they need to be near “Mother” physically?
Whether one feels the Mother’s love or not depends on whether one is open to it or not, it does not depend on physical nearness. Openness means the removal of all that makes one unconscious of the inner relation — nothing can make one more unconscious than the idea that it must be measured only by some outward manifestation instead of being felt within the being; it makes one blind or insensitive to the outward manifestations that are there. Whether one is physically far or near makes no difference; one can feel it, being physically far or seeing her little; one can fail to feel it when it is there, even if one is physically near or often in her physical presence.
Sri Aurobindo, The Mother with Letters on the Mother, CWSA volume 32, pages 507 – 508.