Nick Joaquin is one of the Philippines' greatest ever writers, so it's a wonderful idea to explore his work, but it's really best that you do so for yourself, as you'll learn more about Joaquin's characters, setting, plots, themes, moral symbolism and point of view that way. Then again, there are plenty of places where you can go for extra help:
- Film versions have been produced of the two Joaquin short stories you mentioned. A version 'May Day Eve' appeared in the 1977 film Babae ngayon at kailan man, while 'The Summer Solstice' became the 2001 film Tartarin. You could watch those films to get a flavor of the original stories, especially in terms of character and plot.
- 'May Day Eve' appears better served online than the other story, with analysis available at seasite.niu.edu and litreact.com/reactions, although there is a summary of 'The Summer Solstice' at brighthubeducation.com/homework-help-literature.
- The novel 'Caves and Shadows' is discussed at goodreads.com and scribe.com, which are always good places to read about what others think of novels. These are community forums, so you will need to join up first. There is also one reader's particular take on the novel available at valmar.wordpress.com.
Another good place to look is Blurtit! Check out past answers about Nick Joaquin at What Is The Theme Of Nick Joaquin's Story May Day Eve? and What plot of summer solstice by nick Joaquin?
There are other adaptations, often by groups of students, available to watch on YouTube, such as this take on 'May Day Eve'.