Planning to go to China as my first-ever travel experience - what do I need to know?

Hi! I’m planning my first international trip, and I’ve chosen China as my very first destination outside my hometown.

I’m 19 years old from Kazakhstan and I have zero travel experience:

• never traveled alone
• never been on a flight
• never even used a metro/subway before

I invited two friends, but there’s about a 80% chance I’ll be going solo :(

I plan to prepare everything in advance: where to stay, what places to visit, and how to move between cities. My current route looks like: Guangzhou → Chongqing → Chengdu → Shanghai → Beijing

I’m a bit nervous about traveling alone, mostly because of the language barrier, my poor confidence talking to strangers, and the fact that I’ve never used public transport like a metro. Will that be a serious problem in China, or is it beginner-friendly? I’ve already researched the basic apps needed for China travel, such as: Amap, Alipay, DiDi, VPN, Holafly, Dianping, Meituan, Xiaohongshu.

Budget & time: My total budget is about $1,200 USD. Around $500 will be for flights, leaving $700 inside China. I’m planning a 15+ day trip across five cities.

Questions I’d really appreciate advice on:

• Is $700 enough for 15+ days while visiting 5 cities if I travel budget-style?
• Is my route too ambitious for a first-time traveler, or is it manageable?
• How hard is the metro system for someone who’s never used one before?
• How do people usually handle language barriers in daily situations (food, transport, hotels)?
• Are hostels safe and social for solo travelers in China?
• What are the most common beginner mistakes foreigners make in China?
• Anything important I might be not thinking about at all (payments, documents, safety, etiquette, internet, etc.)?

Any advice, warnings, or tips would be really helpful. Thanks in advance!