Roses / Magnolia / Pear tree questions

Hi everyone - I need advice on three questions so if anyone can help, much appreciated.

1. I (successfully) took cuttings of rose bushes last year so I now have some in the garden, plus some others I moved around. Question is this: some of my rose bushes have quite spindly, thin stems now. Am i better to keep cutting them back for the first year or two or let them develop and they'll grow thicker with time??

2. I have a four year old pear tree (Williams) that is already giving a bit of fruit. It's about 7 ft high and seems quite happy. However, it is growing upwards more than sideways. When this season is over, if I keep lopping off the central main branch, would that encourage it to produce more branches lower down or should I leave it??

3. I have a three year old magnolia tree. This year it gave lovely flowers in April. However, now most of the leaves seem to have died off and it looks quite bare. Is this normal for a Magnolia or what do I need to do??

Any advice appreciated.