It sounds like she is a 'highly sensitive' temperament with a very big personal space bubble for sure - hopefully as time passes and trust is built in her friends and environment she will be able to be more resilient to people moving about around her while not having the need to let out a war cry!

As for eating I so agree with the others ... everyone comes for meal time and stays until meal time is over .... this has dual purpose cause it is the 'safest' way to supervise multiple children cause if some are playing and some are eating it means 'some' are being unsupervised while eating or vise versa and that could lead to inappropriate behaviour and choking

So you come to the table and you are offered the food that everyone else is being served and no you do not have to 'eat' but you have to come keep everyone company ... I generally find that eventually the 'picky eaters' sitting there seeing everyone else eat TRY things because often picky eating is a combination of 'control' and 'fear' ... they have to see food several times in order to work up the courage to 'taste' it.

I attended a Nutrition workshop at an OEYC a couple years ago and the best advice they gave about meal time is that as the 'adult' it is our role to ensure that we provide a wide range of nutritionally balanced option at consistent regular times each day and to set consistent safety expectations for behaviour around 'meal time' (aka we sit at the table, we do not throw food, we are not 'silly' at the table and so forth or the food is removed) ... it is the child's job to decide if and how much they will eat during those periods and if they decide 'not to' the food is removed at the end of meal time and nothing is served again until the next 'scheduled' meal time .... no GRAZING in between meal times because this is what leads to 'picky control eating behaviours' because they know if they refuse the healthy stuff served they can get a 'less healthy' snack option in between meals like a cookie or cracker or other 'easy to serve' item!

As for refusing to sit in the highchair - I get that could be a safety issue if she is climbing out or throwing a fit ... I would offer two options to her you sit at the table in your chair and NICELY keep us company OR you go to bed for a nap if you are too 'tired' to join us ... eventually she will choose to sit at the table or she will nap and hopefully wake up more charming!