Kiddushin 26: Movable Property can be Acquired with Guaranteed Property

We begin with a new Mishna, which teaches about property that can be used as a guarantee (ie. if the new owner learns that the property was already owed to someone else, the new owner does not lose his/her acquisition).  Such guaranteed property can be acquired by money, document, or possession.  Property that cannot be used as a guarantee - all of the items or 'movable property' in a home, for example - can be acquired by pulling, which is hand to hand acquisition.  However, movable property can also be acquired by money or document or possession as long as it has been somehow attached to land or other guaranteed property.

The rabbis first find proofs for the premises of this Mishna.   How do we know that guaranteed property can be acquired by money? by a document? by possession?  And how do we know that movable property can be acquired by money or by a document?  The rabbis refer to specific proof texts for each assumption.  They consider the case of gifts, as well.  And most interesting to me, they consider the notion of 'possession'.  Proof texts in Jeremiah (40:10) and in Deuteronomy (11:31) suggest that 'dwelling' signifies ownership of a home.  This would give rights to squatters; those in great need of shelter who possess an otherwise unused property.  

In answering a question about whether first fruits must be piled together to transfer their ownership, the rabbis consider the halachot of pe'a.  They note that any size of land is subject to the laws of pe'a, where the produce of at least 1/60 of the land's corners belong to the poor and needy.  So how small might a parcel of land be to transfer ownership of movable property - first fruits, or bikurim - along with it?  The rabbis tell stories of tiny parcels of land (one rabbi "disgusts" another when he uses the apparently useless example of putting a needle in a tiny piece of land to prove his point).  In these cases, people transferred a great deal of movable property to another person through the sale of a minuscule parcel of land.