Albergue Aguario - about 2km from Santiago centre. Rooms are divided into sections of four and there is a good little kitchen. Doors are open until (I think) 12 and you can leave at any time. Reduced rate if you stay for more than one night.
I know that a lot of vegetarians have had problems finding food on the Camino in the past - my sister has recently become a vegetarian. She was expecting to have to eat some meat on Camino but did not have to - bread and cheese became the norm for dinner (we also saw vegetarian 'meat' slices in fridges alongside the sliced meat a couple of times in bigger places but did not try these). For evening meals we either cooked on this Camino (and so often had tinned tuna or sardines) or ate out where she found options. I cannot say how easy it is to find food on the rest of the Camino but on the last 100km it is not too hard to be able to find food.
King Alphonse IX died in Sarria in 1230 while making a pilgrimage to Santiago de Compostela. There is a tower in Sarria and this is all that remains of a medieval fortress. Picture from https://www.google.co.uk/imgres?imgurl=https://fordhamcamino2014.files.wordpress.com/2014/06/image1.jpg&imgrefurl=https://fordhamcamino2014.wordpress.com/2014/06/01/day-7-samos-and-sarria/&h=1536&w=2048&tbnid=bZ2j9iyjgVdinM:&docid=td3zTty4SFDTeM&itg=1&ei=YxqWVpz1N4Sqa5CfpYAC&tbm=isch
Saint James's Day is on Saturday (meaning next year is a Holy Year!) so there's enough time to get cards made and sent out For this craft you'll need blank cards, a map showing the Cami no and boot buttons/cut outs/drawings
In Santiago there are several things that you can do at little cost (I know I have entitled this blog 'free things to do in Santiago' but some of these require a donation).