Well, you don't absolutely have to create a child theme, but if you don't an update to your theme could overwrite your changes. So in future you'll have to update your theme manually which, IMHO, is more difficult than creating a child theme.
Or you could decide to just risk it and update anyway. Or you could decide never to update, even for security fixes. It's your call.
The general answer is still the same. You need to create style rules to give you the effects you want. So you'll probably need to create rules for the
<p> selector in the circumstances you want such as when it's a paragraph inside the main site content or something. And you'll need to create a rule for block quotes to style them however you want them styled.
I just took a look at your site. On the 'Home' page there is only one paragraph starting '1941...' and ending '... Lakehurst, N.J.' So adding paragraph rules won't help on that page. There are paragraph breaks after '...News Service' and after '...Lakehurst, N.J.' and as you can see there is a gap---actually a bottom margin of 24px.
So it seems to me that you need to put the paragraph breaks in as a first step.
The same applies to the article headed, "The declaration and constitution with Larry Arnn". The whole thing is just one paragraph with line breaks (
<br />) instead of paragraphs.
I couldn't find any blockquotes offhand. If you point me to where some should be, I'll take a look.