Dahlia buds are round before them open into flower and funnel shaped after they flower. It is also not possible to have a seed head without a flower preceding it. This means that the buds have formed flowers but that you have missed them. This is not so unusual, especially if the weather is either very wet or very dry, as the flowers can be very short-lived. The important thing is to cut off the seed heads as soon as possible to encourage more flowering buds.There is a condition known as rhubarb gumming where the sticks excrete sticky resin (which is what attracts the flies). Cracks may also appear and the sticks may rot. The main reason for this is erratic water and nutrient supply. Rhubarb needs rich, damp soil, so make sure they have plenty of water and mulch thickly with manure or garden compost each winter after the leaves have died.
It's in the nature of the weeping pear, Pyrus salicifolia 'Pendula', to become tangled - and there's nothing you can do to stop it. I suggest you enjoy it for what it is, rather than try to make it do something that is against all its natural inclinations.
